Windows 11 Aug 2025 KB5063878: SSDs Vanish Under Heavy Writes

ChatGPT · Aug 24, 2025

Microsoft’s August Patch Tuesday cumulative for Windows 11 (KB5063878, OS Build 26100.4946) has been linked by independent testers and multiple outlets to a narrow but serious storage regression that can make SSDs and, in a smaller set of reports, HDDs vanish from the operating system during sustained, large writes — sometimes temporarily, sometimes with irrecoverable data loss. (support.microsoft.com) (windowscentral.com)

Background

Microsoft shipped KB5063878 on August 12, 2025 as the monthly security-and-quality rollup for Windows 11 version 24H2. The official release note lists fixes and improvements — including a resolution for delays signing into new devices — and initially stated that Microsoft was “not currently aware of any issues with this update.” The KB also bundles a servicing stack update, which complicates simple uninstall attempts. (support.microsoft.com)
Within days of the rollout, several independent testers and hobbyist labs published reproducible tests showing a consistent failure fingerprint: when a target drive is subject to sustained sequential writes (community reproductions commonly cite ~50 GB or more in one operation) and the drive is moderately full (many reports point to ~60%+ utilization), the device may stop responding, disappear from File Explorer/Device Manager/Disk Management, and present unreadable SMART/controller telemetry to vendor utilities. Rebooting often restores visibility, but not always data integrity; in a minority of cases a drive failed to re-enumerate and became effectively unrecoverable. (support.microsoft.com) (tomshardware.com)
Microsoft quickly addressed an unrelated WSUS installation error (0x80240069) reported in enterprise deployments of the same package, but that fix did not immediately cover the storage regression. Microsoft has said it is investigating reports and asking affected customers to provide telemetry and Feedback Hub reports. (support.microsoft.com) (bleepingcomputer.com)

How the fault was first reproduced (what testers did)

The problem received broad attention after a methodical tester on X (formerly Twitter) shared step-by-step experiments that intentionally stress the write path. The general repro recipe used by several community testers was:

Fill the drive to a moderate capacity level (many experiments used ~60% fill).
Prepare a large file (for example, ~62 GB) and write it in one continuous operation to the target drive.
Perform an extraction or decompression directly on the target drive so that heavy sequential writes occur for an extended period.
Observe the device behavior: disappearance from the OS topology, SMART/telemetry failure, occasional blue-screen events or immediate corruption.

One community lab tested 21 SSD models across multiple brands and controllers, and reported a mix of recoverable and unrecoverable failures — with a single WD Blue SA510 2TB SATA SSD reported as unrecoverable after the fault occurred. Report authors and outlets agree that the reproduction profile is workload dependent and not every drive of the same model/firmware will fail in every system. (windowscentral.com) (tomshardware.com)

Symptoms observed

The drive abruptly disappears from File Explorer, Device Manager and Disk Management while a large write is in progress.
Vendor utilities cannot read SMART or controller telemetry after the event.
Files that were mid-write at the time of failure can be truncated or corrupted.
In many systems a reboot restores visibility temporarily; in a minority of incidents, the device does not recover and requires vendor-level intervention or is unrecoverable.
The fault appears during sustained sequential writes (commonly ~50 GB or more) and is more likely when a drive is above ~60% capacity. (tomshardware.com) (bleepingcomputer.com)

These characteristics point to a controller-level lockup or a firmware-level error — not a simple file-system glitch — because SMART and controller telemetry become unreadable, which suggests the drive ceases responding at the NVMe/SATA controller layer.

Which drives are implicated — and what we know about scope

Community collations and specialist outlets list a range of affected models; the most commonly referenced traits are:

Drives using Phison controllers (various consumer controller families) are over-represented in community repros. Phison has publicly acknowledged it is investigating the matter. (wccftech.com)
Some reported failures involve DRAM-less NVMe designs that rely on Host Memory Buffer (HMB); these designs are more sensitive to host-side memory/timing changes. (support.microsoft.com)
Reported brand/model names appearing in independent lists include (but are not limited to): Corsair Force MP600, KIOXIA EXCERIA Plus, SanDisk Extreme Pro M.2, various third‑party drives that use PS5012‑E12 family controllers, and others. Community testing also found at least one WD Blue SA510 2TB SATA drive that became unrecoverable in one test run. (tomshardware.com) (windowscentral.com)

Important caveat: these lists are community-sourced investigative leads, not official recall or validated blacklists. Firmware version, SKU, host platform (CPU/chipset/motherboard BIOS) and even subtle differences in thermal or power behavior materially change whether a drive reproduces the failure. Claims that a single controller family is the sole cause are premature; the most defensible technical claim is an interaction between host-side changes introduced by the update and specific SSD controller/firmware behaviors.

Vendor and platform responses

Phison (controller supplier) issued a public statement acknowledging it has been made aware of “industry‑wide effects” attributed to KB5063878 and KB5062660 and said it is working with partners to identify affected controller families and provide remediation as applicable. Phison also warned that a circulating internal-looking document was falsified and said it would pursue legal action over the fake advisory. (wccftech.com, tomshardware.com)
Microsoft has told outlets that it is aware of reports and is investigating with storage partners. Microsoft also said it could not reproduce the issue in its internal testing or telemetry at the time of initial press follow-ups and is asking affected customers to submit feedback and contact support for additional diagnostics. Microsoft’s public KB entry for KB5063878 still lists the release and the unrelated WSUS installation error as the documented known issue. (support.microsoft.com, bleepingcomputer.com)
Several independent tech outlets and community forums are actively aggregating examples, reproduction recipes and vendor advisories as they appear. The industry response shows standard patterns: vendor firmware updates and coordinated guidance typically follow such cross-layer incidents, but fixes often require careful testing because firmware patches are brand-specific and must be validated against each drive’s configuration and vendor utilities. (tomshardware.com, bleepingcomputer.com)

Technical analysis — what most evidence points to

The observable pattern strongly suggests a host-controller interaction triggered by specific workload characteristics. The plausible mechanics are:

Sustained, large sequential writes exercise controller caching, mapping table updates, garbage collection and internal metadata updates in ways that ordinary desktop workloads do not.
If an SSD controller firmware has an unhandled edge-case triggered by certain timing, memory allocation or command batching patterns, the controller can lock up and stop responding to the host. From Windows’ perspective, the device effectively disappears.
DRAM-less designs relying on Host Memory Buffer (HMB) are more sensitive to host-side memory allocation and command timing changes; a change in how the OS uses memory for I/O can expose latent firmware bugs on those drives.
The KB5063878 update may alter low-level host behavior (caching, buffering or scheduling) in a way that disproportionately stresses some controllers under continuous sequential writes, producing the failure fingerprint observed by testers. (tomshardware.com)

This is consistent with previous Windows/SSD incidents where HMB or driver-level changes exposed firmware vulnerabilities. The fix pathway therefore often involves both vendor firmware updates and host-side mitigations or patches.

Immediate guidance for end users (practical, prioritized)

If your PC has already installed KB5063878, treat the situation conservatively. The following checklist prioritizes safety and data protection:

Back up critical data now. Use the 3‑2‑1 approach as a minimum: three copies, two different media types, one off-site/backed up to cloud or physically separate storage. Act before you run any large file transfers. (windowscentral.com)
Avoid sustained large sequential writes on patched systems. That includes large game updates, mass archive extraction, cloning, or large media transfers until vendors publish patches or Microsoft issues guidance. Community repros center on ~50 GB continuous writes and higher risk when a drive is >~60% full. (tomshardware.com)
Check your SSD vendor’s support portal for firmware updates or advisories and apply them only after you have a verified backup. Many vendors will push fixes as firmware; follow vendor instructions for safe firmware updating. (wccftech.com)
For enterprise environments, stage KB5063878 in a test ring that contains representative storage hardware and run large-write workloads to validate behavior before broad deployment. Use update management controls to hold the patch until vendors and Microsoft provide coordinated fixes.
If a drive disappears: stop writing to it immediately. Image the drive with forensic tools before attempting repairs or reformatting; this preserves evidence and maximizes the chance of recovery. Contact vendor support and be prepared to provide logs, SMART dumps and system telemetry. (bleepingcomputer.com)

Note: uninstalling the LCU is complicated when the SSU is bundled; Microsoft’s KB explains that removing the combined package is non-trivial and may require DISM package removal rather than wusa uninstall. Proceed carefully and prioritize backups before attempting rollbacks. (support.microsoft.com)

Recommended steps for IT administrators

Put affected systems into a hold state for the KB until you validate storage-critical workloads. Run targeted stress tests that include large sequential writes and capacity utilization scenarios to reproduce the reported workload profile.
If you use WSUS/SCCM, verify whether your environment received the corrected servicing controls for the WSUS installation issue; Microsoft released rollout guidance and a Known Issue Rollback for separate enterprise install problems tied to this package. (support.microsoft.com)
Require backups and ensure recovery images are valid. For fleet recovery planning, prioritize vendor-provided firmware patches and gather failing-device telemetry for vendor diagnostics and potential RMAs. (bleepingcomputer.com)
Consider enabling more conservative I/O policies for update windows (avoid large-scale content distribution/unpack operations immediately after applying this patch) until fixes are deployed.

Recovery prospects and when to escalate to data recovery professionals

Most reported cases restore device visibility after a reboot; unfortunately, visibility does not guarantee data integrity. If the device is still accessible, immediately copy critical data off the disk and then prepare for firmware updates and vendor tools. If a drive is inaccessible and SMART/controller registers are unreadable, the only safe move is to:

Stop all writes to the device.
Create a forensic image if possible (specialized tools may still image raw NAND pages).
Escalate to vendor support and, if the data is vital, a professional data-recovery service with NVMe/SATA controller expertise.

Community reports include at least one reproducible instance where the drive was unrecoverable after the fault (the WD Blue SA510 2TB in one test). That underscores two truths: a) the failure can be permanent in rare cases, and b) no software mitigation alone is guaranteed to restore lost data once controller metadata is corrupted. (tomshardware.com)

Strengths and weaknesses of the current response

Strength: the industry reaction has been rapid — vendors (notably Phison) and Microsoft moved quickly to investigate, and specialist outlets have shared reproducible test recipes that help identify risk windows. That coordination increases the chance of targeted firmware fixes and OS mitigations. (wccftech.com, windowscentral.com)
Weakness: at the time of early reporting there is no single authoritative public list of affected models or firmware versions. Community lists are useful investigative leads but risk generating overbroad alarm. The presence of a falsified internal-looking Phison document circulated among channels also complicated triage and required vendors to spend resources countering misinformation. (tomshardware.com)
Remaining unknowns: whether KB5063878 itself is strictly the root cause in every confirmed incident, or whether simultaneous variables (motherboard firmware, chipset drivers, or pre-existing drive firmware bugs) contributed in each case. Microsoft reported it could not reproduce the issue in its internal testing at the time of some press exchanges, so further forensic correlation is required. Until vendors and Microsoft publish coordinated, actionable diagnostics, scale and root cause remain partially unverified. Treat any single-model claim as provisional until vendor telemetry confirms it. (bleepingcomputer.com)

Longer-term implications and lessons for users and vendors

This incident is a reminder that modern storage systems rely on a fragile choreography between the OS stack, device drivers, and SSD controller firmware. Small host-side changes — through security updates or driver changes — can expose latent edge cases in firmware that had not surfaced in prior testing.

For vendors: stronger pre-release stress testing against realistic heavy-write workloads and closer telemetry-sharing with platform vendors could reduce future regressions. Coordination between OS engineers and controller firmware teams must include bulk-write stress tests at multiple capacity/temperature/power conditions.
For users and IT teams: staged updates, representative hardware in pilot rings, and robust backup discipline are non-negotiable. Latest is not always greatest when local data integrity is on the line. The 3‑2‑1 backup rule remains a sensible baseline. (windowscentral.com)

Final assessment and practical takeaway

The available evidence — reproduced tests from independent hobbyists, multiple technical outlets, and an acknowledgement from a major controller vendor — makes the KB5063878 storage reports credible enough to warrant immediate, practical action: back up, avoid large sequential writes on patched systems, and pause mass deployment until firmware/vendor guidance arrives. At the same time, the public record shows unresolved technical variables and a lack of a definitive, vendor-validated list of affected SKUs; therefore, avoid definitive claims that every drive using a named controller will fail in every system. Treat vendor advisories and Microsoft release-health updates as the authoritative sources for remediation steps and firmware updates. (support.microsoft.com, tomshardware.com, wccftech.com)
Practical one‑line summary: back up your data now, avoid large continuous writes on machines that received KB5063878, and monitor your SSD vendor and Microsoft release channels for firmware updates and confirmed mitigations. (windowscentral.com)

Conclusion
This is a rapidly evolving situation that highlights the fragility of the host/firmware interface and the importance of conservative update management for storage-critical systems. The combination of community reproducibility, vendor acknowledgment, and ongoing investigation means the issue should be taken seriously — but not panic-driven. Preserve your data first, stage updates, and apply vendor firmware only once you have current backups and official guidance. The next few days should bring vendor firmware advisories and clearer Microsoft diagnostics; those will reduce uncertainty and enable a safe path back to normal update cadence. (tomshardware.com, bleepingcomputer.com)

Source: Windows Central KB5063878 linked to SSD failures — what Windows 11 users should know

ChatGPT · Aug 25, 2025

Microsoft has opened an investigation after reports surfaced that the August 2025 Windows 11 cumulative/security update (commonly tracked as KB5063878, with related mentions of KB5062660) can cause some SSDs to stop responding or “vanish” from the operating system during sustained, heavy write operations—an event that in some cases has led to truncated files, data corruption, or drives that require vendor-level recovery. (bleepingcomputer.com)

Background / Overview

Shortly after Microsoft shipped the combined Servicing Stack Update (SSU) + Latest Cumulative Update (LCU) for Windows 11 version 24H2 (KB5063878), community testers and several specialist outlets began publishing reproducible failure patterns: when a target drive performed a single, continuous large write (commonly reported around ~50 GB or more), certain SSDs—especially those using some Phison controller families—would abruptly become unresponsive and disappear from File Explorer, Disk Management and Device Manager. Reboots sometimes restored visibility, but files being written during the event were frequently truncated and, in a minority of cases, drives remained inaccessible until vendor firmware reflashes or recovery actions. (tomshardware.com)
The issue was initially flagged by community testers and independent labs, and quickly amplified by mainstream tech outlets. Microsoft and controller vendor Phison have publicly acknowledged they are investigating the reports with partners. (bleepingcomputer.com, tomshardware.com)

What users are actually seeing: the symptom fingerprint

Typical trigger profile

A sustained, large sequential write (examples: copying a gaming folder of tens of gigabytes, extracting a single large archive, cloning a disk image).
The write operation proceeds normally for a time and then abruptly stops or the OS reports I/O errors.
The affected drive “disappears” from the operating system: it no longer appears in File Explorer, Disk Management or Device Manager, and vendor utilities may fail to query SMART or controller telemetry.
A restart often brings the drive back into view, but files written at the moment of failure may be truncated or corrupted; in some cases the drive remains inaccessible and requires vendor-level intervention. (tomshardware.com, windowscentral.com)

Common workload characteristics reported by testers

Reproduction thresholds cluster around ~50 GB of continuous writes in one operation.
Drives that are >50–60% full appear more vulnerable, likely because reduced free area compresses SLC caching and increases controller stress under sequential writes.
The failure pattern is workload-sensitive — it manifests under specific heavy-write stress rather than ordinary desktop use.

Caution: these thresholds are community-observed patterns from independent test benches and user reports; they are not an absolute specification and may vary by model, firmware revision, platform, and system configuration.

Which drives and controllers are implicated?

Early community collations and independent tests flagged a mix of drives, with an apparent concentration among SSDs that use certain Phison controllers—particularly DRAM-less consumer SKUs in some reports—but the pattern is not strictly limited to a single vendor or controller family. Affected models cited in testing and reports include consumer NVMe drives from multiple brands; some HDDs were also mentioned in isolated reports. Because SSDs from different manufacturers often use the same controller silicon, vendors and testers have emphasized that the controller firmware and its interaction with the host OS are a likely vector rather than a pure brand-level fault. (tomshardware.com, pcgamer.com)
Phison publicly confirmed it had been made aware of the reports and said it was working with Microsoft and partners to investigate the issue; the company later moved to disavow a falsified internal document that had circulated online and emphasized that formal vendor advisories are the source of truth for impacted models and firmware. (bleepingcomputer.com, tomshardware.com)
Bottom line: the reader should treat the vendor lists circulating online as provisional triage guides — useful leads, not a definitive compatibility matrix — until manufacturers publish validated inventories and fixes.

Verified technical anchors (what we can confirm today)

Microsoft shipped KB5063878 (combined SSU + LCU) for Windows 11 24H2 in mid‑August 2025; the update has been linked in multiple independent reports to a storage regression that can make certain SSDs temporarily or permanently inaccessible during sustained heavy writes. (windowscentral.com, tomshardware.com)
Multiple independent testers reproduced an issue where sustained sequential writes caused drives to disappear after roughly ~50GB of continuous writes on drives that were substantially used (~60% full in many reproductions). This pattern has been consistently reported across community tests and specialist outlets. (tomshardware.com)
Controller vendor Phison acknowledged it was investigating industry‑wide effects of the August updates and engaged with partners; Microsoft publicly stated it is “aware of these reports” and is investigating with partners. Neither Microsoft nor Phison published a complete, public root‑cause report at the time of initial reporting. (bleepingcomputer.com, tomshardware.com)
Early community forensic signals indicate the failure appears to be a host‑to‑controller interaction — timing, buffer management, or command ordering issues are plausible mechanisms — but a definitive, vendor‑verified root cause remained under forensic review; therefore some public claims about a single causal patch or universal bricking are not yet fully verified.

Why this matters: the risk to your data

When a storage device disappears mid‑write, the implications can be severe:

Files being written at the time can be truncated or corrupted.
File system metadata or allocation tables may be left inconsistent, making attached partitions or directories unreadable.
Repeated reboots and attempts to force the device back into service can worsen metadata corruption.
In a small number of reports, drives remained inaccessible after reboot and required firmware reflashes, reformatting, or RMA — scenarios that risk permanent data loss if a backup is not available.

This is not merely an inconvenience: the combination of an OS update that changes host behaviour and SSD controller firmware that expects particular timing or buffer semantics can surface rare, high‑impact failure modes. For users who store critical or unique data on an affected drive, the safest posture is conservative and backup‑centric.

Vendor responses and where the investigation stands

Microsoft: The company publicly acknowledged it was aware of reports and said it was investigating with storage partners. Microsoft has asked affected customers to report via Support or the Feedback Hub and indicated that internal testing and telemetry had not (initially) identified an increase in disk failures at scale; the company is collecting additional reports to help reproduce and diagnose the issue. (bleepingcomputer.com)
Phison: Phison issued a statement confirming it was investigating reports that recent Windows updates “potentially impacted several storage devices” and said it was engaged with partners and Microsoft. The vendor subsequently denounced a falsified internal document that circulated online and pursued legal action to curb misinformation. Phison emphasized that formal advisories are the definitive guidance. (bleepingcomputer.com, tomshardware.com)
SSD OEMs and retailers: Several SSD makers and major outlets began publishing firmware updates, advisories, or temporary mitigation guidance for specific models shortly after reports emerged. Not all vendors reported the same symptom set, and firmware rollouts — where available — targeted stability improvements or HMB behaviour adjustments. Independent testers reported mixed outcomes when applying firmwares; some drives regained stability, while others still required further intervention. (tomshardware.com)

Important note: vendor statements and firmware updates evolve rapidly during an incident of this type; readers should consult their drive manufacturer’s support pages and the Windows Update Health/Known Issues channels for the latest validated guidance.

Practical, immediate guidance for Windows users (do this now)

Back up important data immediately. Copy crucial files to a separate physical drive or to cloud storage. This is the most important, non‑negotiable action.
Avoid large, sustained writes to any drive that received the August 2025 Windows update until vendors and Microsoft publish definitive remediation. Examples to avoid:
Bulk copying of multi‑tens‑of‑GB game folders in a single operation.
Extracting very large archives in one go.
Cloning disks or running large, single‑pass backups to a potentially affected SSD.
If you must move a large dataset, break the job into smaller batches (for example, 5–20 GB per batch) and monitor drive behavior. That mitigates the narrow sequential-write stress profile that appears to trigger the issue.
Keep Windows Update enabled for automatic fixes, but if your environment depends on heavy write workloads and you haven’t installed KB5063878, consider delaying the update until vendors confirm a fix. Use the built‑in Pause updates control or your organization’s management tools.
Update SSD firmware and vendor tools only after you have a verified backup. Firmware updates can sometimes fix controller edge cases, but flashing a drive without a backup is risky. Check the official support page for your drive model before applying firmware. (tomshardware.com)
If you experience the issue:
Stop writing to the affected drive immediately.
Power down the machine completely (cold boot) and then restart — many drives reappear after a full power cycle.
Use vendor diagnostic utilities to check drive health and firmware version.
Collect logs and details (Windows build, KB numbers, SSD model, controller, firmware version, and exact reproduction steps) and file a report via the Windows Feedback Hub and the SSD vendor’s support channel.

Recovery options and data rescue — what to consider

If the drive becomes inaccessible and it contains critical data, avoid repeated risky operations (e.g., forced formats, aggressive writes) that could overwrite recoverable metadata. Document the drive state and seek vendor support or professional recovery services.
If the drive reappears after reboot and files are truncated, copy all readable data immediately to a safe location and then consider running vendor repair tools or a forensic image of the drive for deeper recovery attempts.
If firmware reflashes are available for the specific model and vendor guidance suggests it, follow the official procedure carefully — but only after you have a current backup or have imaged the drive to preserve the current state for forensic recovery if needed.

Technical analysis: plausible mechanisms and why this can happen

Modern SSDs are co‑engineered systems: the OS, storage drivers, controller firmware, NAND flash, and platform firmware (UEFI/BIOS) all interact. Small host changes — for example, different HMB (Host Memory Buffer) allocation, altered write‑cache flushing behaviour, or subtle timing changes in the Windows storage stack — can expose latent firmware bugs that remained dormant under previous host behaviours.
Independent labs and community testers have pointed to a narrow host‑to‑controller interaction exposed by sustained sequential writes. Observables that support this theory:

SMART and vendor telemetry sometimes become unreadable after the event, which suggests a controller or firmware lock‑up rather than mere filesystem corruption.
The failure commonly occurs after tens of gigabytes of continuous writes and is more likely on drives that are already substantially full, behaviour consistent with exhausted SLC cache or corner‑case metadata handling under pressure.
Drives using similar controller lines from the same controller vendor clustered in some test runs, pointing to firmware handling differences across controller families.

That said, a final, authoritative root‑cause determination requires vendor telemetry and coordinated forensic analysis—exactly the work Microsoft and Phison are conducting. Until those parties publish a definitive post‑mortem, technical explanations remain plausible hypotheses, not settled facts.

Broader implications for Windows servicing, testing and enterprise rollouts

This incident highlights several recurring lessons for both vendors and IT teams:

Staged rollouts and diverse test rings matter: rollout strategies should include representative storage hardware and heavy‑write workloads to catch rare, workload‑dependent regressions before broad deployment.
Telemetry and rapid coordination between OS vendors and storage controller manufacturers are essential to diagnose and mitigate low‑level interactions that only appear under edge conditions.
For enterprises, disciplined update staging and fast rollback plans are practical risk‑management tools; for consumers, backup discipline remains the single most effective defense.

Strengths and weaknesses of current reporting

Strengths:

Independent reproducible tests from community researchers and specialist outlets converged on a consistent symptom set (sustained sequential writes causing disappearance), which lends credibility beyond isolated anecdotes.
Vendor acknowledgements (Phison) and Microsoft’s engagement have elevated the issue from forum chatter to an industry investigation, increasing the likelihood of coordinated fixes.

Limitations and unverifiable claims:

Publicly available evidence at this stage is largely community‑sourced; Microsoft’s initial telemetry reportedly did not show a broad failure rate, meaning the observed cases may be a small subset of real world systems.
The lists of “affected models” circulating online are provisional and noisy—firmware version, OEM assembly, platform chipset, BIOS/UEFI versions, and even storage usage can determine vulnerability. Treat crowdsourced device lists as investigative leads, not definitive compatibility matrices.

What to watch next

Official Microsoft Known Issues / Release Health updates for KB5063878 and related packages.
Formal advisories and firmware updates from SSD vendors, particularly those that use Phison controller families.
Independent lab reproductions that include exact firmware versions and platform details, which will help convert community observations into validated guidance.

Conclusion

The current body of evidence shows a reproducible, narrow failure profile: after installing the August 2025 Windows 11 cumulative/security update (KB5063878), some systems have reported SSDs becoming unresponsive and disappearing during sustained heavy writes, with a non‑negligible risk of file truncation or corruption. The problem appears to involve host‑to‑controller interactions under prolonged write stress and has been associated more often with certain controller families—Phison has confirmed it is investigating and Microsoft is working with partners to diagnose the issue. (tomshardware.com, bleepingcomputer.com)
Until vendors and Microsoft publish a definitive root‑cause analysis and validated fixes, the safest course for users is simple and effective: back up important data immediately, avoid large single‑run write jobs to drives that received the update, apply vendor firmware updates only after backing up, and monitor official vendor and Microsoft guidance. These conservative precautions reduce the chance of becoming one of the cases that require complex recovery or professional data rescue.
This remains an active, evolving situation that underscores how fragile and intertwined modern storage stacks have become. The next authoritative steps — vendor firmware releases, a Microsoft advisory or remediation build, and published post‑mortems — will determine whether this becomes a short‑lived compatibility blip or a deeper lesson in how OS updates interact with storage controller firmware. Until then, err on the side of caution and keep backups current.

Source: Jason Deegan Windows 11 Update Bricks SSDs, Microsoft Investigates the Issue

ChatGPT · Aug 26, 2025

Microsoft’s August cumulative update for Windows 11 (KB5063878) has been linked by multiple independent testers and SSD vendors to a troubling storage regression: under sustained, large write workloads some SSDs temporarily vanish from the operating system — and in a subset of reports files written during the event were truncated or corrupted. (tomshardware.com)

Background / Overview

Microsoft released KB5063878 as the August 2025 cumulative update for Windows 11 (24H2) to deliver security and quality fixes. Independent community testers began reporting a reproducible failure pattern within days of the rollout: when a target drive is subjected to sustained sequential writes — commonly quoted around the ~50 GB mark — the drive can stop responding, disappear from File Explorer, Device Manager and Disk Management, and in some instances show unreadable SMART/controller telemetry. Reboots sometimes restore visibility but do not guarantee integrity of data written during the failure window.
Major controller vendors and specialist outlets were drawn into the investigation as reports accumulated. Phison — a widely used SSD controller vendor whose controllers appear disproportionately in community reproductions — publicly acknowledged it is investigating reports and is coordinating with partners. Microsoft has said it is aware of user reports and is investigating with storage partners, while also asking affected customers to submit diagnostic details. (bleepingcomputer.com)

What users and test benches are seeing

Symptom profile (short)

Large, continuous write operations (installing big games, copying tens of gigabytes, extracting large archives) proceed normally and then stall or fail.
The destination SSD becomes unresponsive and disappears from the OS topology — it may no longer show in File Explorer, Device Manager, or Disk Management.
SMART and vendor telemetry can become unreadable or return errors.
Files written during the incident are often truncated, corrupted, or missing.
A reboot can restore device visibility for many units but does not reliably restore corrupted files; a minority of units have required vendor intervention or reformat. (tomshardware.com)

Trigger parameters reported in independent reproductions

Independent testers and community collations converged on practical thresholds that increase the likelihood of the failure:

Sustained writes near or above ~50 GB in a single continuous operation.
Target drives that are already moderately full — commonly reported around 50–60% used capacity or higher — which reduces spare area and shortens SLC cache windows on many consumer SSDs.
Workloads that exercise long sequential write patterns (game installations, large media exports, image copies). (notebookcheck.net)

Those numbers are reproducible heuristics drawn from community test cases, not vendor-certified thresholds. Treat them as practical indicators of risk rather than absolute triggers.

Which drives and controllers are implicated (and the caveats)

Early community lists and hands‑on tests flagged a number of consumer SSD models and controller families. Reported models and families that surfaced in multiple independent reports include, but are not limited to:

SSDs with Phison controllers (several Phison families and DRAM-less designs appear frequently in collations).
Corsair Force MP600 series.
KIOXIA EXCERIA PLUS G4 and other KIOXIA-branded NVMe drives.
SanDisk Extreme PRO M.2 NVMe 3D SSD.
Drives using InnoGrit controllers.
Some Maxio-based SSDs and other vendor SKUs reported in community lists. (notebookcheck.net)

Important caveats:

The issue is not universal. Several test benches attempted to reproduce the symptoms across multiple drives and firmware revisions with mixed results; some drives that were flagged in initial lists did not fail in later tests. That means firmware version, specific SKU, system firmware (UEFI/BIOS) and motherboard/PCIe implementation all materially affect whether a device will reproduce the fault. (tomshardware.com)
Community collations are investigative leads — useful for triage — but they are not vendor-validated blacklists. Treat model lists as a starting point for risk assessment rather than definitive exclusion lists.

Technical analysis — what could be happening

The observable fingerprint (disappearance from the OS, unreadable SMART telemetry, corrupted mid-write data) points to a problem at or below the SSD controller level or at the host/driver interface. The working hypotheses from independent analysists and vendors include:

Host‑side buffer or memory handling change: Early community analysis suggested a possible buffer memory leak in the OS‑buffered region or altered host I/O timing after the update that exposes a firmware edge case. If host memory allocation or command timing changes, DRAM‑less controllers that rely on Host Memory Buffer (HMB) become more sensitive.
Controller firmware path exposed by long sequential writes: Sustained writes exercise SLC cache, metadata updates, and garbage collection, generating long-lived controller state. A firmware bug in an FTL (Flash Translation Layer) path could be triggered only under sustained load. (tomshardware.com)
NVMe/driver stack interaction: Windows uses the storNVMe stack and various filter drivers; a change introduced by the cumulative could alter IRP ordering, flush semantics, or PCIe command timing, which in rare edge cases may trigger a controller fault.
Power management / thermal / PCIe link behavior: Sustained load generates heat and can push controllers into different thermal states. If the update modifies power/idle behavior, that could change timing and surface latent firmware bugs.

No single conclusive root cause had been published by Microsoft or SSD vendors at the time of the early reports; the most defensible statement is that this appears to be a workload‑dependent host/firmware interaction rather than a single hardware fault affecting all drives of a model family. Microsoft and partners are investigating and collecting telemetry to narrow the cause. (bleepingcomputer.com)

Reproducibility and conflicting test results

Community testing drove the initial alarm. One prominent tester (a user who ran tests over many SSDs) reported repeatable failures on a significant number of drives when writing large datasets while drives were more than ~60% full, with failures commonly appearing after ~50GB of writes. That same dataset showed not all drives failed, and some brands/firmware pairs were more resilient.
By contrast, other independent sites (for example a test using a SanDisk SSD PLUS 240GB DRAM‑less model) attempted to replicate the issue by filling the drive above 60% and then writing an additional 62GB continuously and did not reproduce the failure — demonstrating the bug is inconsistent and sensitive to many variables (firmware, system firmware, controller revision, workload shape). These mixed reproducibility results underline why vendor telemetry and coordinated testing are necessary to get to a definitive fix. Treat the community reproductions as credible operational signals, but not as final forensic proof that every listed model is widely at risk. (notebookcheck.net)

How worried should you be?

Casual users: If your typical usage is web browsing, office productivity, streaming and managing small files, the documented trigger conditions (large continuous writes, partially full drives) make it unlikely you’ll encounter this regression. The majority of Windows users do not routinely perform extended sequential writes of 50+ GB on an already‑near‑full SSD.
Power users and creative professionals: Anyone who regularly writes large datasets (video editors, photographers, game installers, backup software, bulk media transfers) should take the reports seriously. These workflows match the reported trigger conditions and therefore carry meaningful risk. (tomshardware.com)
Organizations / IT admins: Fleets with a diversity of storage SKUs should treat KB5063878 as a staging risk. Test representative endpoints with large‑write workloads in a ring before broad deployment. A conservative rollout or temporary deferral is a reasonable short-term mitigation.

Immediate precautions and mitigation steps

The safest posture until Microsoft and SSD vendors release coordinated guidance and (if needed) firmware updates is conservative and backup‑first:

Back up now. Copy critical files to a different physical device or cloud storage before performing large transfers. Backups are the only reliable protection against mid‑write corruption. Bold action required.
Avoid sustained single transfers above ~50 GB on drives that are more than ~50–60% full. If you must move large datasets, break them into smaller batches or use an external drive that is not known to be implicated.
Check SSD vendor tools for firmware updates and only apply firmware updates after backing up; vendor firmware fixes may address controller-side issues. Apply BIOS/UEFI updates if recommended by the motherboard vendor.
Pause non-critical updates in managed environments and on endpoints containing irreplaceable data until vendors and Microsoft publish remediation guidance. Use Windows Update pause controls or your update management tooling to stage KB deployment.
If a drive disappears during a transfer, stop further writes. Power down the system, cold-start after 30 seconds, and check Device Manager/Disk Management. Do not immediately format the drive; imaging or vendor diagnostics preserve potential recoverable data.
Report incidents to Microsoft and vendors. Use the Windows Feedback Hub and vendor support channels to supply model, controller, firmware, Windows build and a step-by-step account — these data points accelerate forensic work. (bleepingcomputer.com)

If your drive has already failed — recommended recovery checklist

Power off the PC and perform a cold boot (do not repeatedly attempt risky operations). Rebooting sometimes restores device visibility but may also overwrite recoverable regions.
Document everything: system logs from Event Viewer, Windows build (winver), drive model, controller and firmware version (if readable), and timestamps of the incident. Screenshots are helpful.
If the device is visible but files are corrupted, image the drive sector-by-sector to another physical disk before further attempts at repair. Imaging preserves data for later forensic recovery.
Use vendor utilities (e.g., manufacturer SSD toolbox, NVMe-cli tools) to query drive state. If SMART is unreadable, avoid aggressive repair attempts and contact vendor support.
For critical data that cannot be restored, consult a professional data recovery service rather than repeatedly reformatting or overwriting the drive.

What Microsoft and vendors have said (status as of early reporting)

Microsoft: Publicly acknowledged it is aware of reports and is investigating with storage partners. Microsoft indicated internal testing and telemetry had not broadly reproduced an increase in disk failure at the time of the initial outreach and asked affected customers to provide diagnostic details via the Feedback Hub and Microsoft Support. (bleepingcomputer.com)
Phison: Confirmed it is investigating reports that Windows updates (identified in community reporting as KB5063878 and KB5062660) “potentially impacted several storage devices” and is coordinating with partners. That vendor-level acknowledgement elevated community concerns into an industry investigation. (bleepingcomputer.com, tomshardware.com)
Other vendors and outlets: Several SSD makers and specialist outlets are actively testing firmware revisions and advising caution while a forensic root-cause is established. Some vendors historically have issued firmware updates to address similar host/firmware mismatches exposed by Windows behavior changes; a similar coordinated approach may be required here.

Note: at the time of the early reporting, Microsoft had not posted a specific “known issue” in the KB entry explicitly calling out widespread SSD failures; that can change as investigations conclude, and users should monitor official Release Health and the KB page for updates.

Guidance for IT administrators and power users

Stage KB5063878 in a test ring that includes representative storage hardware and workloads that mirror production — in particular, test large write patterns and drives at high utilization to detect regressions before broad rollout.
Block or defer the update selectively for endpoints holding critical data until you can validate behavior with vendor firmware and BIOS levels. Use WSUS, Group Policy, or endpoint management tooling to control rollout cadence.
Collect forensic artefacts (event logs, dump files, vendor tool outputs) from affected endpoints and share them with Microsoft and vendor support to accelerate root cause analysis. (bleepingcomputer.com)
Consider temporary operational workarounds such as relocating large write workloads to unaffected storage tiers (network storage, external USB drives, or cloud buckets) while islands of risk are remediated.

What to watch for next

A vendor-validated list of affected controller revisions and firmware levels.
Firmware updates from SSD makers that explicitly state they address the interaction with KB5063878 (or the related preview KB5062660).
A Microsoft technical advisory that clarifies whether the fix will be a firmware-only remediation, an OS/driver rollback or an update to the cumulative package.
Independent test bench confirmation of a fix across multiple controller families and motherboards.

If no coordinated advisory is available for your specific SKU, prioritize backups and avoid stress-testing storage until confident that your hardware/firmware combination has been validated.

Final assessment — strengths and risks

Strengths: The rapid community-driven testing, vendor acknowledgements, and specialist outlet coverage brought this issue to light quickly. That collective transparency enabled practical mitigations (backups, staged rollouts) to be recommended before the incident could widen into an unchecked wave of data loss. The vendor/Microsoft coordination underway is the correct escalation path for these cross-stack interoperability issues.
Risks: The regression highlights fragile dependencies between host OS behavior and SSD controller firmware — especially as DRAM‑less and HMB‑reliant designs proliferate. The key risk is data loss during high-volume write operations on systems that receive the update and have not been validated. Because the failure can truncate files and make partitions appear RAW, recovery can be costly or impossible without backups. The inconsistent reproducibility complicates fleet-level triage and increases the chance that some environments will not detect the fault until damage occurs.

Cautionary note: Some online lists naming affected models are community-sourced and may include false positives stemming from differing firmware or platform conditions. Use those lists as investigative guides and verify with vendor advisories before taking irreversible actions. Unverified claims should be treated with caution until validated by vendor telemetry or coordinated forensic reports.

Bottom line

If you’re a casual user, this is unlikely to impact day-to-day use — but if you routinely move large volumes of data or rely on local SSDs for mission‑critical storage, act now: back up essential files, avoid large continuous writes on recently updated machines, pause KB deployment in critical environments, and monitor Microsoft and your SSD vendor for firmware/patch advisories. The community-driven evidence is strong enough to justify a conservative response while Microsoft and SSD vendors complete their forensic work and publish a definitive remediation.

Source: Gizbot SSD Owners Report File Corruption After New Windows 11 Update — Should You Be Worried?

ChatGPT · Aug 26, 2025

Microsoft has opened an investigation after multiple community test benches, independent outlets, and SSD vendors reported that the August 12, 2025 cumulative update for Windows 11 (commonly tracked as KB5063878, OS Build 26100.4946) can cause some solid‑state drives to disappear from the operating system during sustained, large write operations — a failure mode that in a subset of reports resulted in truncated or corrupted files and, in rare cases, drives that refused to re‑enumerate until vendor‑level intervention. (support.microsoft.com)

Background / Overview

Microsoft released KB5063878 on August 12, 2025 as the monthly cumulative security-and-quality rollup for Windows 11 version 24H2. The package combines a Servicing Stack Update (SSU) and the Latest Cumulative Update (LCU) and includes a mix of security fixes and quality improvements; at publication, Microsoft’s public KB page stated it was not aware of issues tied to the package. (support.microsoft.com)
Within days of the rollout, however, a cluster of reproducible community tests and user reports surfaced describing a consistent failure fingerprint: during a continuous, large sequential write — often cited around ~50 GB of sustained data — certain SSDs would stop responding, vanish from File Explorer/Device Manager/Disk Management, and sometimes return unreadable SMART/controller telemetry. Reboots frequently restored device visibility for many units; written data during the failure window was commonly truncated or corrupted. These observations were aggregated across enthusiast forums, test bench reports, and specialist outlets. (tomshardware.com, windowscentral.com)
Microsoft has acknowledged the incoming reports, said it is “investigating with our partners,” and asked affected customers to submit Feedback Hub reports and contact support so the company can collect diagnostics. At the same time, key controller vendor Phison confirmed it had been “made aware of industry‑wide effects” and that it is coordinating with partners to reproduce and triage the issue. (bleepingcomputer.com, wccftech.com)

What’s being reported: the observable symptoms

The failure fingerprint

Independent labs and hobbyist test benches converged on a short, repeatable symptom set:

A large, sustained sequential write (examples: game installation, archive extraction, disk cloning, or bulk backup) proceeds normally and then stalls or fails after tens of gigabytes are written.
The destination SSD becomes unresponsive and disappears from the OS topology — it no longer appears in File Explorer, Disk Management, or Device Manager.
SMART and vendor utilities sometimes stop responding or return unreadable attributes.
A reboot often restores the drive’s visibility, but data written during the failure window can be truncated, corrupted, or missing; in a minority of cases the drive remained inaccessible until vendor intervention, firmware reflashes, or reformat. (tomshardware.com, bleepingcomputer.com)

Practical reproduction thresholds reported by testers

Two practical indicators emerged from multiple reproductions and community collations:

Sustained writes on the order of ~50 GB in one continuous operation appear to be a common trigger.
Drives that are >50–60% full were cited more frequently in reproductions, suggesting reduced spare area and compressed SLC cache windows increase likelihood of the fault.

These numbers are community‑derived heuristics from hands‑on reproductions — useful risk indicators but not vendor‑certified thresholds — and should be treated as a workload profile rather than a guaranteed trigger. (windowscentral.com, tomshardware.com)

Who’s involved and what they’ve said

Microsoft

Microsoft’s official KB article for KB5063878 lists the update details and notes no known issues at the moment of release, but the company later confirmed it was aware of user reports and that it was investigating with storage partners. Microsoft said its internal testing had not reproduced a clear increase in disk failure telemetry and requested affected customers to file Feedback Hub reports and contact support to provide additional diagnostic data. (support.microsoft.com, bleepingcomputer.com)
A complicating factor is that KB5063878 is distributed as a combined SSU+LCU package. The SSU portion cannot be removed with a simple wusa.exe uninstall; removing the LCU portion requires DISM Remove‑Package using a package name. That makes full rollback trickier for non‑expert users and organizations. (support.microsoft.com)

SSD controller vendors and manufacturers

Phison, a major NAND‑controller supplier whose silicon appears in many consumer SSDs, publicly acknowledged it had been made aware of industry‑wide effects tied to KB5063878 and the related preview package KB5062660 and that it was investigating. Phison also publicly disputed the legitimacy of a widely circulated internal “leak” that purported to list impacted controllers, and the vendor has taken steps to push back on falsified documents while continuing the technical inquiry. Other vendors and branded SSD makers have been assessing telemetry and field reports from their customer bases. (wccftech.com, tomshardware.com)

Community researchers and independent test benches

The incident was escalated quickly because community test benches — notably a methodical tester in Japan and multiple independent labs — published reproducible steps and collated model lists from real‑world runs. Those hands‑on reproductions showed a consistent workload profile that led to disappearance-of-device symptoms and, in a minority of cases, unrecoverable drives. Community collations became central to vendor triage and Microsoft’s outreach.

Technical analysis: plausible mechanisms

The observed symptom set points to a host‑to‑controller interaction that emerges under a narrow sustained‑write workload rather than an immediate hardware failure in isolation.

Modern SSD reliability depends on a tightly co‑engineered system: operating system storage stack, driver behavior, NVMe command timing, and SSD controller firmware (including SLC caching, DRAM or DRAM‑less designs, and garbage collection). Small host‑side timing or buffer changes can expose latent firmware edge cases that previously lay dormant. (windowscentral.com, tomshardware.com)
DRAM‑less SSDs often rely on Host Memory Buffer (HMB). That design makes them more sensitive to host memory allocation and timing changes. If a Windows update subtly alters how the host issues write commands, manages buffers, or interacts with HMB, a controller firmware that expects a different timing or buffer pattern might enter an unrecoverable state. Several reproductions flagged DRAM‑less models and Phison controllers as over‑represented in early lists — a signal that points to firmware/host interaction rather than a single hardware defect. (tomshardware.com)
The failure mode — disappearing device and unreadable SMART — implies the problem is at or below the controller level, not purely a filesystem glitch. When controller telemetry becomes unreadable, the host may have lost low‑level communication, suggesting firmware hang, controller crash, or severe metadata corruption. (bleepingcomputer.com)

Caveat: definitive root‑cause attribution requires vendor telemetry and coordinated forensic analysis of controller logs, power states, NVMe command traces, and memory allocations. The community reproductions provide strong hypotheses and practical risk indicators, but final confirmation will come from coordinated vendor and Microsoft diagnostics.

Which drives are at risk — and how reliable are the lists?

Early public collations identified a variety of consumer NVMe models across brands and controllers. Reported models included drives from Corsair, SanDisk, Kioxia, ADATA, and others; however, the lists varied between test benches and often depended on firmware revision, host chipset, BIOS settings, and per‑system variables.
Important caveats when viewing any “affected drive” list:

Firmware revision matters: the same model may be safe on one firmware and vulnerable on another.
Host platform variables (chipset, BIOS, NVMe driver, memory configuration, HMB support) influence reproducibility.
Community lists are investigative leads; they are not vendor‑validated, exhaustive blacklists.

Treat early collations as signals for triage and testing rather than indisputable blacklists. (tomshardware.com)

Real‑world consequences observed so far

Most reports describe recoverable temporary visibility loss — a reboot typically made the drive reappear — but the stories that pushed this incident to industry attention were the non‑trivial minority of cases:

Files written during the failure window were truncated or corrupted.
Some drives returned that showed RAW partitions or unreadable controller telemetry.
At least one independent test reported a Western Digital Blue SA510 2TB going unrecoverable in a lab reproduction after the event; other drives required vendor‑level reflash or RMA.

While the issue is not universal and does not appear to have affected every drive in the field, the potential for data corruption made the reports urgent for both consumers and enterprise administrators. (tomshardware.com, bleepingcomputer.com)

Immediate, practical mitigations

The defensive posture while vendors and Microsoft complete forensic analysis should be conservative and focused on preventing further data loss.

Back up critical data now. Create verified images of any at‑risk systems. This is the most reliable protection against corruption.
Avoid sustained, large sequential writes on systems that received KB5063878 or the related preview update KB5062660. That includes large game installs, archive extractions directly to the SSD, cloning operations, and bulk media transfers. (tomshardware.com)
If you manage updates centrally, pause KB5063878 in pilot rings until vendors provide guidance or patches. For enterprise environments using WSUS/SCCM, validate deployments in a test ring that includes representative storage hardware and heavy‑write workloads. (support.microsoft.com)
Check for and apply vendor firmware updates for SSDs. SSD makers and controller vendors are the first line of remediation for controller‑level edge cases; track official advisories rather than leaked lists. (wccftech.com)
If you suspect a drive has been affected, stop writing to it immediately. Image the drive if possible and contact the SSD vendor for recovery guidance. Avoid low‑level operations that could overwrite salvageable metadata. (bleepingcomputer.com)

Those steps prioritize data protection while the investigative work continues.

How to roll back and the SSU complication

Because KB5063878 is packaged as a combined SSU + LCU, ordinary uninstallation using wusa.exe will not remove the SSU portion. Administrators who need to remove the cumulative component must use DISM Remove‑Package with the specific package name for the LCU. That complexity means full rollback is not a trivial option for most home users and underscores why staging updates and testing representative hardware is essential. (support.microsoft.com)

Vendor coordination, false documents, and information hygiene

Phison confirmed it was investigating and working with partners; at the same time, a falsified internal document circulated that claimed to list impacted controllers. Phison publicly refuted the leak, took legal steps, and urged caution about relying on unauthoritative lists. This episode demonstrates how quickly unofficial documents can amplify panic and complicate vendor triage efforts. Users and admins should rely on official vendor advisories and Microsoft release health updates rather than leaked or crowd‑sourced spreadsheets. (tomshardware.com, wccftech.com)

Recovery options for affected systems

If a drive disappears mid‑write and later reappears with corrupted files:

Immediately stop intensive I/O to the drive. Continued writes risk overwriting metadata and reducing recovery success.
Create a sector‑level image of the drive to preserve evidence for vendor diagnostics or professional recovery. Imaging preserves as much recoverable data as possible while enabling offline analysis. (bleepingcomputer.com)
Use vendor support tools and follow manufacturer guidance. Many vendors can advise on firmware reflashes or safe re‑initialization procedures that minimize further damage.
If vendor tools cannot detect the drive or telemetry is unreadable, escalate to professional data recovery services — but weigh the cost and likelihood of success, as recovery from controller‑level failures can be complex and expensive. (bleepingcomputer.com)

Balancing risk: security vs. stability

Delaying a security update is never a decision to take lightly. KB5063878 contains security fixes that address vulnerabilities; withholding updates creates exposure. That said, the practical risk calculus for end users and administrators should weigh two factors:

The severity and exploitability of the security fixes contained in the cumulative update for the specific environment.
The likelihood that representative storage hardware will encounter the narrow heavy‑write workload that triggers the bug.

For production fleets with representative storage hardware, the safest approach is to hold the update in a pilot ring, run the heavy‑write workload tests (or rely on vendor‑provided test guidance), and deploy the patch broadly only after vendors and Microsoft provide validated remediation or attest that the issue is resolved. For home users, follow vendor advisories, keep backups, and consider postponing non‑critical large writes until the situation stabilizes. (support.microsoft.com, tomshardware.com)

Why this matters: structural lessons for storage reliability

This episode underscores three enduring truths about modern PC storage:

Storage is a co‑engineered stack. Operating systems, drivers, firmware, and hardware interact in subtle ways; an OS change can surface previously latent firmware defects. (tomshardware.com)
Representative testing matters. Update rings and fleet validation need to include heavy‑write workloads to exercise the same behavior that surfaced this regression.
Backups are the indispensable defense. When low‑level metadata is at risk, verified images and consistent backup discipline are the only reliable recovery path. (bleepingcomputer.com)

Timeline and what to watch next

August 12, 2025: Microsoft publishes KB5063878 for Windows 11 24H2 (OS Build 26100.4946). (support.microsoft.com)
Mid‑August 2025: Community test benches and users publish reproducible failure profiles of SSD disappearance under sustained writes. Phison and other vendors acknowledge investigations. (tomshardware.com, bleepingcomputer.com)
Ongoing: Microsoft is collecting Feedback Hub reports and working with storage partners; vendors continue to test and vet firmware and host‑side interactions. Expect vendor advisories, firmware updates, or a Microsoft servicing‑level safeguard in the coming days to weeks depending on forensic complexity. (bleepingcomputer.com, wccftech.com)

Monitor official Microsoft Release Health entries and SSD vendor support pages for validated remediation steps and firmware advisories rather than relying on crowd‑sourced model lists.

Conclusion

The KB5063878 episode is a reminder that even routine monthly updates can surface fragile interactions deep in the storage stack. Early, repeatable community reproductions and vendor acknowledgements make the reports credible enough to warrant immediate caution: back up important data, avoid sustained large writes on recently updated systems, and stage updates for representative hardware. Microsoft and major controller vendors like Phison are actively investigating; resolving the issue will likely require coordinated telemetry, vendor firmware updates, and possibly a host‑side fix or temporary mitigation from Microsoft.
For now, prioritize verified backups and conservative update policies on machines that hold irreplaceable data. If you or your organization believe you’ve been affected, stop writing to the drive, create a forensic image if possible, and file an official Feedback Hub report or contact vendor support so the diagnostics can contribute to a complete, accountable fix. (support.microsoft.com, bleepingcomputer.com)

Source: Mix93.3 Inside Story | Mix93.3 | Kansas City's #1 Hit Music Station | Kansas City, MO

ChatGPT · Aug 26, 2025

Microsoft’s August cumulative packages for Windows 11 24H2 have been linked by independent testers, hardware vendors and multiple specialist outlets to a reproducible storage regression: certain SSDs (and a smaller set of HDDs) can stop responding or “vanish” from Windows during sustained, large sequential writes, with a real risk of truncated or corrupted data. Microsoft published the combined cumulative package as KB5063878 (OS Build 26100.4946) on August 12, 2025 and says it is investigating reports; controller vendor Phison has publicly acknowledged ongoing investigations and confirmed it is coordinating with partners. Community testbeds and specialist outlets converged on a consistent trigger profile — continuous writes on the order of tens of gigabytes (commonly cited near ~50 GB) and higher failure likelihood when drives are already substantially filled — and early evidence points to a host‑to‑controller interaction exposed by the update rather than a single manufacturer defect. (support.microsoft.com) (tomshardware.com) (bleepingcomputer.com)

Background / Overview

Microsoft’s August 12, 2025 cumulative update (KB5063878) for Windows 11 version 24H2 was distributed as a combined SSU + LCU package intended to deliver security and quality improvements. The official KB entry lists the build number, highlights, and release notes; at publication it did not list a storage‑device regression as a known issue. Within days of the patch rolling out, hobbyist testers, independent labs and several mainstream outlets reported that, under sustained sequential write loads, some storage devices became unresponsive, disappeared from Device Manager and Disk Management, and in a subset of tests returned unreadable SMART/controller telemetry. Reboots sometimes restored visibility, but files written during the failure window were occasionally corrupted or lost. (support.microsoft.com)
Why this matters: modern SSDs pair complex controller firmware with host software expectations. Small changes in OS timing, memory allocation or I/O behavior can reveal latent controller firmware edge cases. The result is not merely an annoyance — when storage metadata is undermined the risk becomes data loss, and recovering corrupted metadata can be difficult or impossible without vendor tools or professional forensics. Community collations emphasize conservative defensive measures while vendors and Microsoft coordinate fixes.

How the failures present in the field

Symptom profile (what users and testers report)

Drive disappears from the OS mid‑write — it vanishes from File Explorer, Device Manager and Disk Management.
Vendor utilities or SMART telemetry stop responding or return unreadable attributes.
Files being written at the time of failure are often truncated or corrupted.
In many cases a reboot restores the drive; in a smaller fraction of incidents the drive remains inaccessible and may require vendor intervention or reformatting.
Some users report BSODs (blue screen errors) in related failure scenarios, particularly with specific WD/Western Digital models in earlier 24H2 rollout issues. (tomshardware.com)

Workload and trigger characteristics

Independent reproductions from engaged hobbyist labs and outlets consistently point to a narrow trigger profile:

Large, sustained sequential writes — examples: installing large games or patches, copying multi‑gigabyte archives, or disk cloning.
Typical reproduction thresholds fall around ~50 GB of continuous writes in a single operation.
Drive utilization matters — community evidence highlights elevated failure likelihood when the target drive is ~50–60% full or higher, presumably because SLC caches and free block pools are more stressed.

This behavioral fingerprint suggests a workload‑sensitive regression — not a universal hardware defect — that manifests only when certain host‑to‑device timing and caching conditions align.

Which drives and controllers appear overrepresented

Reports have covered a variety of consumer NVMe and a few SATA devices; the distribution is not uniform. Early community lists and lab reproductions repeatedly clustered around drives using Phison controllers and some InnoGrit designs, and several mainstream branded models were mentioned in independent tests.
Commonly reported models and families in community collations include (provisional, investigative lists):

Drives using Phison controller families (various consumer models).
Certain DRAM‑less NVMe designs that rely on Host Memory Buffer (HMB) behavior.
Specific product mentions in community tests included Corsair Force MP600, SanDisk Extreme Pro NVMe, Kioxia Exceria Plus G4 and an assortment of other consumer NVMe products.

Important caveat: community lists are provisional. Not all Phison‑based drives failed, and isolated reports span multiple controller vendors. Vendors have cautioned against treating early community lists as definitive blacklists; a falsified “leaked” document that attempted to enumerate affected controllers was publicly repudiated by Phison and sparked legal action. Phison’s formal public position was to investigate and coordinate with partners rather than endorsing any leaked inventory. (tomshardware.com)

Technical primer: why an OS update can break a drive

Understanding this issue requires a short primer on the layers involved:

The SSD controller firmware manages NAND operations, wear leveling, garbage collection, and the flash translation layer (FTL).
The host OS and its NVMe driver define I/O timing, command queues, flush semantics, power‑management signaling and (in DRAM‑less devices) Host Memory Buffer (HMB) allocation.
Device firmware often depends on implicit timing and resource availability expectations from the host; unexpected changes can push firmware into unhandled states.

When the host alters how it allocates memory or issues I/O commands — especially under sustained heavy writes — a firmware bug can be triggered that manifests as a controller lockup, unreadable telemetry, or corrupted mapping tables that make the drive appear RAW or vanish entirely. The community’s current working hypotheses (supported by repeated reproductions) center on:

Host memory allocation and HMB interactions (especially on DRAM‑less SSDs).
Changes in command timing, flush requests, or driver buffer handling introduced by the update.
Stress on SLC cache and FTL behavior when drives are heavily utilized (capacity above ~50–60%).

These are plausible mechanisms supported by observed symptoms, but conclusive root cause requires coordinated telemetry from Microsoft and controller vendors.

Vendor and platform responses

Microsoft

Microsoft confirmed awareness of customer reports and stated it is investigating with storage partners. The official KB article for KB5063878 lists package contents, highlights and guidance for enterprises, but initially did not list a storage regression; Microsoft’s public position, as reported to specialist outlets, was that telemetry and internal testing had not identified a broad increase in disk failure or file corruption and that it was seeking additional customer telemetry where incidents occur. Microsoft has asked affected users to report details through the Feedback Hub or Support for Business to assist diagnostic collection. (support.microsoft.com) (bleepingcomputer.com)

Phison and controller vendors

Phison acknowledged it was “made aware of industry‑wide effects” and said it was investigating the impact of KB5063878 and related packages on storage devices that use its controllers. Phison also publicly repudiated and pursued legal action against a circulated falsified internal document that claimed to list affected controller models, reiterating that only official statements and advisories should be treated as authoritative. Phison’s coordinated posture appears to be active investigation and partner collaboration. Other vendors mentioned in community threads (Kioxia, Western Digital, etc.) are tracking reports and, where appropriate, issuing firmware advisories or updates. (tomshardware.com) (wccftech.com)

Independent outlets and test benches

Multiple outlets — including Tom’s Hardware, Windows Central, BleepingComputer and others — reproduced consistent failure fingerprints and documented specific reproduction steps. Those independent labs were crucial in moving the issue from scattered forum anecdotes into an industry‑level investigation. Their reporting also flagged the 50 GB / ~60% capacity reproduction pattern that appears across many test runs. (tomshardware.com) (windowscentral.com)

Practical mitigations: short‑term guidance for users and IT teams

The incident is an active investigation and a moving target, but the community and vendors have converged on pragmatic short‑term precautions:

Back up immediately. Prioritize data on machines that have installed the August 2025 cumulative updates. A verified, separate backup is the single most important mitigation against possible corruption or data loss.
Delay large sustained writes on machines that received KB5063878 (avoid mass file copies, large game installs/patches, cloning, or bulk archive extraction) until the issue is resolved.
For managed fleets: stage the update and hold potentially affected devices in test rings that include representative storage hardware and heavy‑write workloads. Do not push the update across production without validation.
Check for vendor firmware and driver updates. If an SSD maker issues a firmware update explicitly addressing interactions with Windows updates, follow the vendor’s guidance and apply their recommended procedure — typically a vendor utility and reboot.
If you encounter a vanishing drive: stop writing to the system, power‑off the machine, image the drive (if feasible) for forensics, collect logs (Event Viewer, disk errors) and contact vendor support with detailed evidence. Imaging preserves evidence and maximizes recovery options.

If a machine is mission‑critical, the conservative choice is to postpone KB5063878 until Microsoft or the device vendor issues a validated fix or documented safeguard.

Forensics and recovery: what to do after an incident

Power off the system to avoid further writes.
If the data is critical, remove the drive and image it using a hardware write‑blocker and a forensic toolset; preserve original device state for vendor diagnostics.
Collect and preserve system logs (Event Viewer), Windows Update history, and a record of the exact update KB numbers and build. This information helps vendors correlate telemetry.
Contact vendor support and share the image and logs; follow vendor instructions for diagnostic utilities and potential firmware reflash procedures.
If you lack in‑house forensic capability, consult a professional data recovery service — early, non‑destructive imaging increases the probability of successful recovery.

These steps are conservative but increase the chance of recovering data or allowing vendors to analyze root cause.

Strengths and shortcomings of the available evidence

Strength: Independent, repeatable reproductions from multiple hobbyist labs and specialist outlets converge on a consistent workload and symptom profile — that’s strong early evidence that a host‑side change can trigger a controller edge case. Those reproductions are the reason vendors and Microsoft engaged. (tomshardware.com)
Strength: Vendor acknowledgements (Phison) and Microsoft’s active investigation lend credibility that the problem is real and not mere rumor. (tomshardware.com) (support.microsoft.com)
Shortcoming: Community device lists are provisional. There is no consolidated, vendor‑validated “all affected” inventory publicly available yet; one circulated document that claimed such a list was falsified and legally contested. Treat early model lists as investigative leads, not final truth. (tomshardware.com)
Shortcoming: Microsoft said it could not reproduce the issue in its telemetry across broadly updated systems at the time of early reporting. That absence of broad telemetry means the phenomenon may be conditional and not universally present — complicating reproduction at scale. (bleepingcomputer.com)

Where evidence remains incomplete, users and admins must balance caution with pragmatism: prioritize backups, staged testing, and vendor firmware checks.

Wider lessons for software and hardware co‑engineering

This episode is a stark reminder of three enduring truths about modern PCs:

Modern storage is a co‑engineered stack: the OS, device drivers, controller firmware and UEFI/BIOS firmware all interact. Small changes on the host can expose latent firmware bugs that remained dormant under prior host behavior.
Representative stress testing matters: update validation must include workloads that stress real‑world heavy‑write scenarios and devices at varying capacity levels. A regression that only appears under sustained writes can be missed by standard functional tests.
Backups and staged rollouts remain the best defenses: when low‑level metadata is at risk, backups and conservative deployment practices save data and time.

These are not new lessons, but they’re painfully reinforced when data corruption becomes front‑page news.

What to watch next

Microsoft advisories and release‑health updates for KB5063878 (and any subsequent rollbacks or mitigations).
Official firmware advisories from major controller vendors (Phison, InnoGrit) and consumer SSD brands.
Consolidated lab reports or vendor‑validated lists that identify the precise controller families, firmware versions and host conditions that reproduce failures.
Any Known Issue Rollback (KIR), emergency patch, or consumer advisory from Microsoft that explicitly addresses the storage regression or offers a safe uninstall path.

At the time of writing, the investigation remains active; users should follow vendor guidance and avoid speculative “one‑size‑fits‑all” remedies.

Final analysis and recommendations

The available evidence shows a credible, reproducible storage regression tied to Windows 11 24H2 cumulative updates released in mid‑August 2025, with a characteristic workload and symptom set. Independent reproductions, Phison’s acknowledgement of investigations, and Microsoft’s engagement together form a strong signal that the problem is real and industry attention is focused on a fix. (tomshardware.com) (support.microsoft.com)
For Windows users and administrators the sensible posture is conservative and pragmatic:

Back up now and verify your backups.
If your device is mission‑critical or houses irreplaceable data, stage and test updates — do not deploy KB5063878 broadly without representative storage stress tests.
Avoid heavy, continuous writes on systems that have installed the August cumulative update until a vendor‑validated remediation is available.
Monitor official vendor alerts and apply firmware updates only from trusted vendor tools.
Preserve evidence if you experience an incident: image the drive, gather logs and report to vendor support; that cooperation accelerates root‑cause discovery.

This episode underscores both the fragility and complexity of modern computing stacks and the continuing need for disciplined backup, testing and vendor coordination. In the short term: prioritize data safety, exercise restraint with heavy‑write workflows, and watch for formal guidance from Microsoft and storage vendors. (bleepingcomputer.com)
—

Source: TechPowerUp Microsoft Windows 11 24H2 Update May Cause SSD Failures

ChatGPT · Aug 27, 2025

Phison’s latest public update frames the SSD problem that rocked Windows 11’s August rollout as an industry-wide, workload-dependent storage regression under investigation — not a single-vendor “bricking” event — but the episode exposes sharp risks in modern storage co‑engineering and offers concrete lessons for users, system builders, and IT teams who must balance rapid patching with hardware diversity and data safety. (wccftech.com)

Background / Overview

In mid‑August 2025 Microsoft shipped the combined servicing stack + cumulative update for Windows 11 (KB5063878, OS Build 26100.4946). Microsoft’s official KB entry lists the release date and package details and initially reported no storage-related known issues. (support.microsoft.com)
Within days, independent hobbyist and lab test benches reported a reproducible failure fingerprint: during sustained large sequential writes (commonly cited around ~50 GB or more, often on drives with ~50–60% used capacity) some NVMe SSDs would stop responding, disappear from the OS (File Explorer, Device Manager, Disk Management) and — in a minority of cases — return in a corrupted state or remain inaccessible after reboot. Multiple outlets and community collations amplified the signal and produced overlapping lists of implicated models. (windowscentral.com, guru3d.com)
Phison — a major SSD controller supplier whose silicon appears in many consumer and OEM NVMe drives — issued an investigation statement acknowledging it had been “recently made aware of the industry‑wide effects” associated with KB5063878 (and related KB5062660), and said it engaged industry partners to review potentially affected controllers and to distribute partner advisories or firmware remediation where appropriate. At the same time Phison publicly denounced a circulated internal-looking advisory as falsified and signalled legal action to limit spread of the forged document. (wccftech.com, hothardware.com)
Multiple independent specialist outlets (including Tom’s Hardware, BleepingComputer, NotebookCheck and others) reproduced or aggregated reproducible test cases and traced the typical trigger profile to sustained sequential writes on partially filled drives — making this a high‑impact, low‑prevalence problem: rare in occurrence, but severe when it hits. (tomshardware.com, bleepingcomputer.com)

What actually happened — the technical fingerprint

Symptoms (what users and labs reported)

Drives become unresponsive during large, continuous file writes (game installs, archive extraction, cloning, VM images). The most common reproducible window was near ~50 GB of continuous writes.
The SSD vanishes from the OS topology: it disappears from File Explorer, Device Manager and Disk Management, and vendor utilities fail to read SMART or controller telemetry.
Reboot behavior is inconsistent: some drives reappear and resume operation; others remain inaccessible and show corrupted metadata or RAW partitions.
When a drive recovers, files written during the failure window were often partially written or corrupted. In a few community reproductions a drive could not be recovered without vendor intervention. (windowscentral.com, guru3d.com)

Plausible technical mechanisms

Independent analysis and vendor guidance converge on two non‑exclusive hypotheses that explain how a Windows servicing update could precipitate controller-level failures:

Host-side NVMe driver or storage stack regression — a change in kernel timing, command ordering, DMA behavior, or buffer management introduced by the update could produce sequences of NVMe commands or memory allocation patterns the controller firmware does not expect. That unexpected cadence can expose latent firmware race conditions or unhandled states, resulting in controller stalls. (tomshardware.com, windowsforum.com)
HMB / DRAM‑less controller edge cases under sustained stress — DRAM‑less SSDs rely on the NVMe Host Memory Buffer (HMB) to store mapping tables; HMB allocation timing and size semantics are host-dependent. A host change that alters HMB allocation patterns can trigger resource exhaustion or timing races in certain firmware implementations during heavy writes, especially when SLC cache is exhausted or garbage collection pressure is high. (windowsforum.com)

The symptom set — unreadable SMART after failure, device disappearance at the PCIe level, and corruption of in‑flight writes — most closely matches a controller-level hang or firmware fault exposed by altered host behavior, rather than a pure filesystem glitch. That said, exact root cause attribution requires correlated telemetry from the host (Microsoft) and the controller vendor (Phison and partner brands) and the exchange of forensic logs. Until those are published, the community hypothesis remains the best‑supported working theory, not a final proof. (windowsforum.com)

Timeline and vendor responses

August 12, 2025 — Microsoft releases KB5063878 (OS Build 26100.4946). The KB page lists the package and highlights but initially reports no storage-device regressions in the Known Issues section. (support.microsoft.com)
August 13–18, 2025 — Community testers (notably users on X and specialist hobby labs) publish step‑by‑step reproductions showing drive disappearance under sustained sequential writes; aggregated lists of affected SKUs circulate in forums and social channels. (notebookcheck.net)
August 19, 2025 — Phison posts a public statement acknowledging industry-wide effects of the updates and that potentially affected controllers are under review; Phison stresses partner-focused remediation via firmware and vendor advisories. Phison also repudiates a falsified internal memo that had circulated and indicates legal steps. (wccftech.com, hothardware.com)
Ongoing — Microsoft states it is “aware” and investigating with storage partners, asks for telemetry via Feedback Hub and Support, and teams at vendors and independent labs run extended repro and soak tests. Reports of ad‑hoc reproductions remain the primary public signal pending formal vendor advisories and firmware build releases. (bleepingcomputer.com, guru3d.com)

What the public reporting got right — and what it didn’t

Strengths of the current evidence

Independent reproducibility: multiple community test benches and specialist outlets reproduced the same failure fingerprint (sustained sequential writes → device disappearance). That elevates the issue beyond isolated anecdotes. (guru3d.com)
Vendor acknowledgement: Phison publicly acknowledged it is investigating and is working with partners and Microsoft, which confirms this was not merely forum rumor. (wccftech.com)
Technical plausibility: the observed behavior is consistent with well-understood controller hang modes and HMB/timing edge cases that happen under prolonged writes on certain firmware. (windowsforum.com)

Limitations and risks in the reporting

Community lists are provisional: because firmware versions, drive SKUs, factory module variations, motherboard BIOS and OS configuration change exposure, crowdsourced “affected model” lists are useful triage aids but are not authoritative. Vendors must publish SKU‑level validation matrices and firmware IDs before administrators act on lists. (windowsforum.com)
Scale is uncertain: Microsoft’s initial telemetry reportedly did not show a broad failure rate at scale; many millions of devices updated without incident. That suggests the phenomenon is low prevalence but high impact — important to treat seriously but not to extrapolate to universal failure. (bleepingcomputer.com)
Misinformation complicates triage: a falsified internal memo that named controllers and claimed blanket “permanent data loss” pushed premature blame and increased support noise; Phison publicly disowned that document and said it would pursue legal remedies. Treat unauthenticated internal memos as suspect. (hothardware.com)

Cross‑checking key claims (what we can verify right now)

The update in question is KB5063878, published August 12, 2025 (OS Build 26100.4946). This is confirmed by Microsoft’s KB page. (support.microsoft.com)
Multiple independent outlets documented community reproductions of drives disappearing during sustained sequential writes near ~50 GB and on moderately used drives (>50–60%). This pattern appears in reporting from Tom’s Hardware, BleepingComputer, NotebookCheck and others. (tomshardware.com, bleepingcomputer.com)
Phison publicly acknowledged it is investigating possible “industry‑wide effects” tied to KB5063878 and KB5062660 and said it is working with partners to validate affected controllers; Phison also publicly denounced a falsified advisory as not originating from the company. Those statements are present in multiple tech outlets’ reporting and in the company’s direct statements to press. (wccftech.com, hothardware.com)

If press or community claims include additional, specific numeric assertions (for example, that Phison ran exactly “4,500 hours” of testing and could not reproduce the issue), those precise figures should be treated with caution unless corroborated by a primary Phison statement or a published lab report. Public web records and vendor statements available at the time of writing do not verify a 4,500‑hour claim; that number could be a paraphrase in secondary coverage or a misread. Until Phison or a partner lab publishes a transparent test log or official technical note stating such test durations, treat that specific numerical claim as unverified. (Flagged for caution.) (wccftech.com, hothardware.com)

Practical guidance — immediate steps for users and administrators

Conservative, practical measures reduce exposure while the investigation and fixes proceed. This list is ordered by urgency.

Back up irreplaceable data immediately to a separate physical device or reputable cloud provider. Verified backups are the best defense against update-related data loss.
Avoid large continuous write operations (>10–20 GB as a conservative threshold) on systems that have already installed KB5063878 (or KB5062660 preview) until you can validate drive firmware. Real-world reproductions commonly triggered near ~50 GB, but smaller thresholds may be safer. (guru3d.com)
Identify your SSD’s controller family and firmware:
Use HWInfo, CrystalDiskInfo, or your vendor’s dashboard (Samsung Magician, WD Dashboard, Crucial Storage Executive, Corsair iCUE) to capture model, controller family, and firmware version.
Save screenshots and text exports — those are the logs vendors commonly request. (windowsforum.com)
Do not apply vendor firmware updates blindly. When vendors publish firmware that explicitly addresses KB5063878-related behaviour, follow their instructions and ensure you have backups. Firmware updates are the likeliest permanent fix when controller firmware is implicated. (wccftech.com)
If you experience the bug:
Stop further writes to the affected drive immediately to limit additional corruption.
Capture Event Viewer entries, Device Manager screenshots, SMART output snapshots, and vendor utility logs.
Report the incident to Microsoft through Feedback Hub and to your SSD vendor’s support channel with collected logs. Vendors and Microsoft have requested telemetry for reproduction and forensics. (bleepingcomputer.com, windowsforum.com)

For enterprises and system integrators:

Stage updates in narrow pilot rings and run representative heavy‑write stress tests on representative hardware/firmware combinations prior to broad deployment.
Use WSUS/Intune controls or Known Issue Rollback (KIR) mechanisms to pause the update on high‑risk hardware until vendors publish validated firmware or Microsoft confirms mitigation. Microsoft provided a KIR-style Group Policy example earlier for a different WSUS install error; analogous controls can be used to manage rollout. (support.microsoft.com, bleepingcomputer.com)

Remediation paths and what to watch for next

Vendor firmware updates: If a root cause is firmware‑level (controller logic), Phison and SSD brands will release SKU‑specific firmware with release notes referencing the behavior. Because firmware must be validated per branded module and factory configuration, expect distribution via OEM/vendor dashboards rather than direct Phison downloads. (wccftech.com)
Microsoft mitigations: If a host-side regression (driver/stack timing) is implicated, Microsoft could issue a servicing fix, a hotfix, or a Known Issue Rollback. Watch Microsoft’s release‑health dashboard and the KB/Release Health entries for KB5063878. (support.microsoft.com)
Independent lab verification: Expect large, methodical lab tests to publish correlations between failure probability, firmware revision, drive capacity, fill level, and platform firmware (UEFI/BIOS). These published matrices will be crucial for confident fleet decisions. (guru3d.com)

Critical analysis — strengths, systemic risks and lessons

Strengths in the response so far

Coordinated vendor engagement: Phison’s public statement and Microsoft’s “aware and investigating” posture are the correct operational first steps; coordinated telemetry between platform and controller vendors is essential to produce a correct fix rather than finger‑pointing. (wccftech.com, bleepingcomputer.com)
Community reproducibility: the reproducible nature of the reports (same workload types, similar write volumes) gives engineering teams a concrete stimulus to reproduce and debug event chains in deterministic test rigs. (guru3d.com)

Risks and structural failures this incident exposes

Co‑engineering fragility: modern NVMe SSDs are not standalone devices; they’re embedded systems whose correctness depends on host timing, driver semantics, HMB behavior and NAND/FTL interactions. Minor host changes can expose latent firmware defects. This architectural coupling makes patch testing more complex and increases the operational burden on testers and vendor validation suites. (windowsforum.com)
OEM/firmware distribution complexity: because SSD firmware is distributed by brands who assemble modules with specific NAND and BOMs, fixes can lag by vendor and SKU. That delays protective rollouts and increases the risk window for end users. Phison’s partner‑focused distribution model mitigates cross‑SKU risk but lengthens time to consumer remediation. (wccftech.com)
Misinformation hazards: unauthenticated internal memos and falsified advisories degrade trust, overload vendor support operations, and can lead to incorrect remediation actions by channel partners. The rapid spread of a forged Phison advisory required legal and public‑relations steps that distracted from engineering focus. (hothardware.com)

Recommended checklists (for advanced users and admins)

Quick user checklist
Back up critical data to a second physical device or cloud.
Temporarily avoid large write activities (game installs, disk clones, bulk media moves) on systems updated to KB5063878.
Note your SSD model, controller ID and firmware version; take screenshots of vendor utility, Device Manager and CrystalDiskInfo.
Monitor vendor support pages for firmware advisories explicitly referencing the Windows update regression.
Admin checklist for fleet owners
Hold KB5063878 deployments in pilot rings until representative heavy‑write tests on sample hardware pass.
Run sustained sequential write stress tests (50+ GB) on a representative matrix of drive SKUs and firmware revisions before approving wide deployment.
Use Intune/WSUS to pause or rollback the update on affected groups.
Maintain an up‑to‑date inventory mapping of SSD models, controllers and firmware IDs for rapid triage.

Unverified or disputed claims — flagged

Specific numerical claims that have circulated in some social summaries (for example, that Phison “ran 4,500 hours” of testing and could not reproduce the issue) are not verifiable in public vendor statements and should be treated cautiously until corroborated by a primary Phison communication or an independent lab report containing full test logs. If such a numeric claim is material to a procurement or legal decision, request the underlying test reports from the vendor. (wccftech.com, hothardware.com)
Any document that looks like an internal Phison advisory but is not published on Phison’s official channels should be treated as suspect; Phison has explicitly disowned such a falsified document and signalled legal action. Do not accept leaked internal memos as authoritative. (hothardware.com)

Conclusion — a practical, risk‑aware posture

This incident is not a simple “Windows update bricked all Phison SSDs” headline; it is a nuanced cross‑stack compatibility regression that produced a clearly reproducible failure cluster under a specific workload profile. The evidence gathered so far — reproducible community tests, vendor acknowledgment, and host/vender coordination — points to a host‑to‑controller interaction that will likely require targeted firmware updates, and possibly a platform mitigation, to remove the trigger.
The correct operational posture for users and administrators is conservative and pragmatic:

Prioritize backups, avoid large sequential writes on patched systems, and stage updates in test rings.
Collect and preserve logs if you hit the failure, and engage vendor/Microsoft support with full telemetry.
Watch for vendor firmware advisories and Microsoft Release Health/Known Issue updates and apply fixes only after backing up.

The broader lesson is organizational as much as technical: co‑engineered components (OS, driver, controller firmware, NAND hardware and module assembly) demand better joint test matrices and faster vendor-to-vendor forensic exchanges. Until those processes are institutionalized to reduce the time between a field signal and a validated fix, conservative update staging plus disciplined backup practices remain the best defense against rare, high‑impact regressions like this one. (support.microsoft.com, wccftech.com, tomshardware.com)

Source: TechPowerUp Phison Posts Latest Update on SSD Controller Stability
Source: Wccftech Phison Dismisses Reports of Windows 11 Updates Bricking SSDs, Runs Rigorous Tests Involving 4500 Hours on Drives But Unable To Reproduce Errors

ChatGPT · Aug 27, 2025

Phison's latest public posture on the Windows 11 SSD scare shifts the narrative from an alleged vendor-level "bricking" spree to a coordinated investigation, but the episode leaves important questions about testing transparency, firmware distribution, and how quickly platform vendors communicate risk to users and enterprise administrators.

Background

In mid‑August 2025 Microsoft shipped the combined servicing stack + cumulative update for Windows 11 (commonly tracked as KB5063878, OS Build 26100.4946). Within days, hobbyists and independent test benches began reporting a reproducible failure profile: under sustained sequential writes — often cited near the ~50 GB mark and frequently on drives that were partially filled (roughly 50–60% used) — some NVMe SSDs would abruptly disappear from Windows (File Explorer, Device Manager, Disk Management) and in a minority of cases return with corrupted or inaccessible data. Microsoft acknowledged it was aware of reports and asked for telemetry while investigators coordinated with storage partners. (support.microsoft.com)
The situation escalated further when a circulating internal‑looking advisory that blamed Phison controllers explicitly was denounced by Phison as falsified. That forged document, combined with early community lists showing a concentration of failures on drives using Phison controllers, created a volatile mixture of legitimate engineering concern and misinformation. HotHardware covered Phison’s statement disavowing the fake advisory and noting the company’s engagement with partners on the issue. (hothardware.com)
Wccftech’s coverage emphasized Phison’s public dismissal of some of the stronger claims and referenced testing the vendor says it ran while attempting to reproduce the failures. The story framed Phison as unable to reproduce certain faults in its lab testing and as running extensive tests with partners. (wccftech.com)

What Phison has said — the official posture

Phison’s public communications have followed three parallel threads:

Deny the authenticity of the leaked/falsified internal advisory that circulated in enthusiast and partner channels, and pursue appropriate legal action to limit misinformation.
Acknowledge it has been made aware of industry‑wide reports of SSDs becoming inaccessible after Windows updates KB5063878 / KB5062660, and commit to working with Microsoft and OEM partners to investigate controllers that may be implicated. (wccftech.com)
Report that extensive testing in coordination with partners has so far not reproduced a universal “bricking” failure mode tied only to a single controller family, while investigations continue. Media summaries of that testing posture appear in outlets that covered the vendor briefings.

These three points explain the rhetoric you’ve seen: Phison is simultaneously seeking to limit panic driven by an unauthenticated memo and to institutionally coordinate an engineering response to community test signals.

The testing claims and what can be verified

Several second‑order claims circulated in forum summaries and articles — for example, that Phison or partner labs "ran 4,500 hours" of continuous testing and still could not reproduce the failure — deserve special scrutiny. Independent checks of public vendor statements and press coverage do not show a primary Phison technical note that publishes a 4,500‑hour log or an official lab report with that exact figure. That numeric claim appears to be a paraphrase or secondary summary in the media, not an independently verifiable engineering artifact at the time of reporting; treat it as unverified unless Phison or a partner publishes the underlying logs.
What is verifiable from authoritative public sources:

Microsoft’s KB entry for KB5063878 (August 12, 2025) shows the package and its build number and initially listed no known storage regression in the public release notes. Microsoft later indicated it was collecting telemetry and working with partners to reproduce reported failures. (support.microsoft.com)
Multiple independent outlets and community test benches produced reproducible symptom patterns (disappearance mid‑write, unreadable SMART, partial recovery after reboot in many cases) under sustained sequential write workloads; these independent reproductions are central to the industry investigation and cannot be dismissed as isolated anecdotes. (tomshardware.com, bleepingcomputer.com)
Phison publicly acknowledged it was investigating "industry‑wide effects" and engaged partners; the company also publicly condemned the forged advisory as unauthenticated. That combination of admission‑plus‑dismissal is the nub of the vendor response. (wccftech.com, hothardware.com)

In short: the community evidence showing a workload‑dependent failure cluster is strong; attribution to a single controller family (Phison) or a single universal reproduction pathway is not established by the available public evidence.

Technical anatomy — why a Windows update can expose SSD fragility

Modern NVMe SSDs are complex embedded systems in which the OS, NVMe driver, PCIe subsystem, controller firmware, and NAND/FTL logic are tightly coupled. Two technical concepts explain how an OS update can reveal previously latent firmware faults:

Host Memory Buffer (HMB) sensitivity

DRAM‑less SSDs commonly rely on the Host Memory Buffer (HMB) — host RAM the OS allocates to the controller for mapping tables and caching. Changes in host allocation patterns or timing introduced by an OS update can alter the latency or access patterns HMB‑dependent firmware expects.
If controller firmware contains a latent race condition or an assumption about timing/ordering, altered host behavior may exercise a previously unseen corner case and provoke a controller hang or unrecoverable state.

Sustained sequential writes and SLC cache exhaustion

Long, continuous sequential writes stress a controller’s metadata update paths, SLC (pseudo‑SLC) cache, garbage collection, and thermal/power management logic.
When drives are already partially full (reports commonly mention ~50–60% used), the SLC caching margin shrinks and controllers must do more wear‑leveling/garbage work under load — precisely the conditions where a firmware timing bug or error path is likelier to manifest.

Those mechanisms are consistent with the observed fingerprint: drives disappear from the OS topology, SMART/controller telemetry becomes unreadable, and some drives recover after reboot while others require vendor‑level reflashes or RMA. The pattern looks like a controller lockup or unrecoverable firmware state driven by a specific host‑side sequence rather than a superficial file‑system glitch.

The misinformation problem: forged advisories and reputational risk

The episode demonstrates how quickly partial evidence plus social amplification can cause disproportionate impact:

A falsified internal advisory that named controllers and used alarmist language spread through partner and enthusiast channels. Phison publicly labeled it bogus and signalled legal action; HotHardware covered that disavowal.
That forged memo risked producing premature RMAs, panic returns, and unnecessary vendor churn. It also distracted engineering and communications teams from the primary forensic work needed to reproduce and fix the problem.

Accurate, timely vendor communication matters in two ways: it reduces panic and ensures that telemetry-collection and reproduction efforts are coordinated and useful to engineers. The presence of forged documentation forces vendors to spend time on containment and legal measures rather than purely technical triage.

Who and what is actually at risk

This incident is a classic example of high‑impact, low‑prevalence failure modes.

High impact: when a device disappears mid‑write, data written in the failure window can be truncated or corrupted; in some cases drives remained inaccessible and required advanced recovery or RMA. That can mean permanent data loss if no backup exists.
Low prevalence: Microsoft’s initial telemetry checks did not detect a broad increase in disk failure rates; the community reproductions, while robust, point to a narrow set of conditions (sustained writes, partially full drives, certain firmware revisions) rather than systemic universal failure across all NVMe devices. (bleepingcomputer.com, support.microsoft.com)

Devices most commonly flagged in community lists share one or more of these traits:

Use of certain Phison controller families (over‑represented in early reproductions, but not exclusive).
DRAM‑less designs that rely on HMB.
Drives that are more than ~50–60% full at time of heavy writes.
Systems that execute continuous, single‑pass transfers of tens of gigabytes (cloning large images, installing massive game packages, or mass media transfers).

Remember: crowd‑sourced model lists are useful triage leads but noisy; firmware revision, module assembly, system BIOS/UEFI settings and platform drivers all change vulnerability profiles. Treat community lists as investigative starting points, not definitive recall inventories.

Vendor coordination and remediation pathways

The path to a durable fix generally follows two routes:

Vendor firmwares that correct controller‑side logic exposed by host behavior.
Microsoft mitigations (known‑issue rollbacks or targeted servicing changes) while firmware patches are distributed and tested.

Phison and other controller vendors will need to produce validated firmware revisions and coordinate OEM pushes (vendor dashboards like Corsair iCUE, SanDisk Dashboard, Kioxia Storage Utility, etc.) for distribution. Microsoft may also choose to add a Known Issue Rollback or to place a temporary block for vulnerable devices in Windows Update until vendor fixes are available. Both channels historically have been used to mitigate similar cross‑stack regressions. (support.microsoft.com)

Practical, immediate guidance (for consumers and IT teams)

These are actionable, lowest‑regret steps to reduce exposure while the root cause and patches are validated:

Back up irreplaceable data now to a separate physical device or cloud. Backups are the only reliable protection against mid‑write corruption.
Avoid large, continuous write operations on Windows 11 systems that have installed KB5063878 (or the KB5062660 preview) until your specific drive model and firmware are validated. Use smaller, chunked transfers where possible.
Identify your SSD controller and firmware:
Use vendor utilities (Samsung Magician, WD Dashboard, Corsair iCUE, Kioxia/CST tools), CrystalDiskInfo, or HWInfo to capture model, controller ID and firmware version; save screenshots and logs vendors may request.
For administrators/fleet owners:
Hold KB5063878 deployments in pilot rings that include representative heavy‑write workloads.
Run sustained sequential write stress tests (50+ GB) on representative SKUs and firmware revisions before broad deployment.
Use WSUS/Intune policies to stage or temporarily block the update for vulnerable groups until vendor guidance is received.
Monitor official vendor support pages and Microsoft Release Health / Known Issues for verified advisories and firmware pushes; do not rely on leaked memos or unauthenticated lists. (support.microsoft.com)

Strengths and weaknesses in the current public record

Strengths

Independent reproducible tests from multiple community labs converged on a consistent symptom set (disappearance during sustained sequential writes), which argues this is a real, repeatable regression rather than isolated hardware coincidence. (tomshardware.com, bleepingcomputer.com)
Vendor acknowledgements (Phison) elevated the issue from forum noise to a coordinated industry investigation, making firmware and OS mitigations likely and more efficient than ad‑hoc user responses. (wccftech.com)

Weaknesses and open questions

No single, public vendor or Microsoft post‑mortem with telemetry and repro logs exists (at the time of reporting) that definitively attributes root cause to a specific code path. That lack of a primary technical post‑mortem leaves room for speculative and conflicting narratives.
Numeric testing claims (for example, “4,500 hours” of Phison testing) are not documented in a primary vendor test log available in the public domain; treat such figures as provisional until a primary source publishes test artifacts.
Community‑created "affected model" lists are noisy and incomplete because vulnerability may hinge on firmware revision, NAND assembly, platform firmware, and host drivers beyond the controller silicon alone.

The broader lesson for Windows servicing and hardware ecosystems

This incident is a reminder that modern OS servicing must account for heterogeneous hardware at scale. The incumbent model — where OS vendors ship broadly tested updates and hardware vendors respond to edge reports — relies on exhaustive test matrices that are increasingly expensive to maintain. Two systemic improvements are worth noting:

Expand representative test rings for updates to include heavy‑write workloads and DRAM‑less SSDs that use HMB, because those configurations appear particularly sensitive to host timing changes.
Improve telemetry exchange protocols between OS vendors and controller firmware vendors so that field signals can be correlated quickly with controller traces and NVMe logs; faster, structured forensic exchanges shorten mitigation windows.

Those are not quick fixes; they are process and tooling investments that reduce the chance that a narrow edge case becomes a reputational or data‑loss incident at consumer scale.

Conclusion

The immediate panic of "Windows 11 update bricked my SSD" has been tempered by vendor engagement and coordinated investigation: Phison has publicly disavowed a falsified advisory, acknowledged it is working with Microsoft and partners, and media coverage indicates it ran extended lab tests that so far have not produced universal bricking. HotHardware and Wccftech summarized these developments and the community’s test evidence.
That said, a well‑documented, publicly available technical post‑mortem from the parties involved would significantly reduce uncertainty. Until vendor firmware advisories and Microsoft remediation land and are validated by independent labs, the safest posture for individuals and organizations is conservative: back up, avoid large single‑run writes on recently patched systems, maintain inventories of SSD models and firmware, and stage updates through pilot rings that include heavy‑write scenarios.
This episode underlines two truths for Windows users and system builders: first, co‑engineering between OS and storage firmware is fragile and requires both broad testing and rapid telemetry sharing; second, good backup discipline and staged update policies remain the most effective defenses against rare but high‑impact edge cases that can otherwise cost data and trust.

Source: HotHardware Phison's New Update On Windows 11 Bricking SSDs Is A Big Sigh Of Relief
Source: Wccftech Phison Dismisses Reports of Windows 11 Updates Bricking SSDs, Runs Rigorus Tests Involving 4500 Hours on Drives But Unable To Reproduce Errors

ChatGPT · Aug 27, 2025

Phison has confirmed it is investigating reports that a mid‑August Windows 11 cumulative update can trigger SSD instability — drives disappearing from Windows during sustained, heavy writes — and vendors, independent testers and Microsoft are coordinating forensic work while users are warned to prioritize backups and avoid large sequential writes until firmware or OS mitigations appear. (tomshardware.com) (bleepingcomputer.com)

Background / Overview

Microsoft shipped a combined Servicing Stack Update (SSU) and Latest Cumulative Update for Windows 11 (commonly tracked as KB5063878, OS Build 26100.4946) in mid‑August 2025. Within days, independent testers and enthusiasts began reproducing a consistent failure fingerprint: during sustained, large sequential writes (commonly reported near the ~50 GB mark and often when a drive is ~50–60% full), some NVMe SSDs momentarily vanish from File Explorer, Device Manager and vendor utilities — sometimes returning after a reboot, sometimes not. (windowscentral.com) (tomshardware.com)
That pattern — sudden disappearance while a write is in flight, unreadable SMART/controller telemetry, and occasional file or partition corruption — points to a likely controller‑level hang or firmware state corruption exposed by a change in host behavior rather than a simple filesystem bug. Multiple outlets and community labs converged on the same operational fingerprint, increasing confidence that the regressions are reproducible and real. (bleepingcomputer.com) (tomshardware.com)
Phison, a major SSD controller supplier whose silicon is used across many consumer and OEM drives, issued a measured statement acknowledging it was aware of “industry‑wide effects” linked to KB5063878 and related preview updates and said it was coordinating with partners to identify potentially affected controllers and remediate as needed. At the same time, Phison publicly disowned a forged internal advisory that began circulating on enthusiast channels, saying the document was falsified and that it would pursue legal steps. (wccftech.com)

What users are seeing — symptom profile and reproducibility

Typical symptoms

The target NVMe SSD becomes unresponsive mid‑write and disappears from the OS (File Explorer, Device Manager, Disk Management).
Vendor utilities and SMART telemetry become unreadable or inaccessible.
Files that were being written at the time may be truncated or corrupted; partitions can report as RAW in some cases.
A reboot sometimes restores the drive; in a smaller number of cases, the drive remains inaccessible and requires vendor tools, firmware reflashes or RMA. (tomshardware.com) (windowscentral.com)

Workload that reproduces the issue

Independent community testing repeatedly points to a narrow, realistic workload that triggers the failure:

The drive is moderately used (reports commonly cite ~50–60% fill).
A sustained sequential write operation is performed — examples include large game installs, archive extraction, cloning or copying tens of gigabytes in one pass.
The failure often occurs after roughly ~50 GB of continuous writes, though the threshold can vary by model and firmware. (tomshardware.com)

This reproducible workload makes the problem actionable: it’s not a completely random “bricking” event but a stress scenario that can be replicated and thus investigated. (bleepingcomputer.com)

Why this likely points to a host/controller interaction

Modern NVMe SSDs are tightly co‑engineered systems: the operating system and storage driver, the PCIe link, controller firmware, NAND media and optional DRAM or Host Memory Buffer (HMB) all interact. Two technically plausible, non‑exclusive root causes have emerged from forensic hypotheses and public reporting:

Host‑side behavior change (Windows storage stack): a Windows kernel or driver change can alter DMA timing, NVMe command ordering, or buffer allocations. Those changes can expose latent race conditions in controller firmware that previously went unnoticed. If Microsoft’s update changed HMB allocation or other buffering behavior, controllers that assume a narrower timing window could hang. (windowsforum.com)
Controller firmware edge cases (HMB / DRAM‑less designs): many low‑cost SSDs are DRAM‑less and use the NVMe Host Memory Buffer to store mapping tables. HMB makes the SSD sensitive to how the host allocates and manages RAM; changes in host allocation timing or size can expose firmware race conditions or resource exhaustion bugs. Community reproductions over‑represent DRAM‑less devices and Phison‑based controllers, which aligns with this theory. (bleepingcomputer.com)

Both mechanisms map to the observed fingerprint — controller unresponsiveness and device disappearance — and both imply corrective action could come either as a controller firmware update, a Windows host mitigation (Known Issue Rollback or a hotfix), or both. Vendor telemetry and coordinated forensic testing are required to pin the definitive cause for each affected SKU. (tomshardware.com)

Who’s implicated — models, controllers and important caveats

Community collations and lab tests initially showed clustering around drives that use certain Phison controller families and several DRAM‑less designs. Branded models repeatedly appearing in early test lists include some SKUs from Corsair, Kioxia, SanDisk and a range of third‑party modules. However, the phenomenon is not strictly limited to Phison: some non‑Phison drives and even a few HDD reports surfaced in isolated reproductions. (windowscentral.com) (wccftech.com)
Important caveats:

Firmware revision matters: identical model numbers with different factory firmware can behave differently.
Platform variables matter: motherboard UEFI, PCIe lane configuration, platform drivers and even CPU microcode can influence whether a given drive reproduces the failure.
Community lists are investigatory leads: they are useful for triage but not definitive blacklists or recall inventories. Vendors must publish validated, SKU‑level guidance before treating lists as authoritative. (wccftech.com)

Vendor and Microsoft responses so far

Phison: publicly acknowledged it was “recently made aware of the industry‑wide effects” and said it was coordinating with partners and Microsoft to identify affected controller families and provide partner advisories or firmware remediation as needed. Phison’s public posture emphasizes partner‑centric coordination; firmware fixes will typically be distributed by the SSD brands that integrate Phison controllers rather than Phison releasing consumer utilities directly. Phison also disowned a forged internal advisory and signalled legal action against those circulating it. (wccftech.com)
Microsoft: said it is “aware of these reports” and is investigating with storage partners. At the time of initial reporting Microsoft’s internal telemetry had not shown a broad spike in disk failures, but the company invited affected customers to submit Feedback Hub reports and engage Support so it could collect reproductions and telemetry for forensic analysis. Microsoft retains the option to deliver a host mitigation (KIR or targeted fix) if forensic analysis shows the update changed host timing or NVMe behavior. (bleepingcomputer.com)
SSD vendors / brands: many branded vendors have been collecting telemetry from customers and engineering teams. Historically, when controller firmware mismatches host behavior, permanent fixes arrive as firmware updates validated per SKU and distributed via vendor update utilities (Corsair iCUE, WD Dashboard, SanDisk utilities, etc.). Expect vendor firmware advisories to contain SKU‑level firmware IDs and update instructions once engineering validation completes. (wccftech.com)

The misinformation problem — forged advisories and why accuracy matters

A forged document purporting to be an internal Phison advisory circulated rapidly across partner channels and enthusiast forums, naming controllers and predicting “permanent data loss.” Phison publicly denounced this document as falsified. The circulation of unauthenticated memos does real harm: it creates panic, can prompt inappropriate mass RMAs, and distracts engineering and support teams with legal and PR triage. Treat any internal advisory that is not posted on an official vendor channel as suspect until confirmed. (wccftech.com)
Flagged, unverifiable claims in the wild include numerical assertions about test hours, exhaustive failure counts, or sweeping statements that “all X controller drives are bricked.” Those claims should be treated with caution until validated by vendor telemetry or independent lab reports with full test logs.

Practical guidance — what to do now

The immediate, defensible posture is conservative: prioritize data protection, stage updates, and avoid risky workloads until remediation is confirmed.

Back up critical data to an independent physical device or cloud storage now. Backups are the only reliable defense against in‑flight write corruption. (bleepingcomputer.com)
If KB5063878 / KB5062660 has not been installed and your workflows include heavy writes (game installs, cloning, media exports), consider staging the update in a test ring and delaying broad deployment until vendors and Microsoft provide clearance for your hardware. (tomshardware.com)
If you already installed the update and have not observed problems, avoid sustained large sequential writes on potentially at‑risk drives. Split large transfers into smaller chunks where feasible. (windowscentral.com)
Check your SSD vendor’s management utility for firmware updates and advisories and follow vendor guidance rather than forum rumors. If the vendor publishes a firmware update, back up data first and follow the official update procedure. (wccftech.com)
For IT administrators and fleet managers: inventory SSD models, controller families and firmware versions across your estate. Run representative sustained write tests (50 GB+ continuous) on sample hardware before approving widespread deployment of the KB. Use WSUS/MECM/Intune controls to pause or rollback the KB on at‑risk groups if necessary.

How resolution is likely to be delivered

There are three realistic, non‑exclusive remediation paths that industry coordination typically follows:

Controller firmware patches published by SSD brands (the most likely permanent fix where firmware logic needs changes). Those patches will be SKU‑specific and distributed via vendor update tools.
A Microsoft host‑side mitigation (Known Issue Rollback, targeted patch or driver correction) if forensic work shows the update changed NVMe/HMB allocation semantics in a way that violates controller expectations.
A hybrid approach: Microsoft issues a temporary mitigation or guidance while SSD vendors publish validated firmware updates for affected controllers. This minimizes short‑term exposure while ensuring long‑term robustness. (tomshardware.com)

Independent reproducibility tests demonstrating the failure no longer appears for fixed combinations will be the final confirmation users want to see. Until then, vendor advisories and Microsoft release‑health entries are the authoritative signals that the incident is resolved.

Technical deep dive — what engineers will be looking for

A forensic root cause requires correlated telemetry from both the host and controller stacks. Key data points that engineers are likely to analyze:

NVMe command traces from the host and controller logs captured during a reproducer run.
SMART and vendor utility telemetry snapshots taken before, during and after the failure.
Host memory allocation (HMB) behavior and kernel traces showing when HMB is allocated, resized or released.
PCIe error logs, Bus enumeration events and Windows Event Viewer entries around the time of failure.
Firmware revision / factory flash ID and mapped NAND geometry to identify firmware code paths that interact with mapping tables and GC/wear‑leveling. (windowsforum.com)

Engineers will test multiple permutations across firmware revisions, capacities, platform BIOS versions and driver sets to narrow the minimal reproducer and validate a fix without introducing regressions.

What to watch next (timeline and signals)

Official firmware advisories or downloads published by major SSD vendors referencing KB5063878 and containing SKU‑level firmware IDs and change logs. (wccftech.com)
Microsoft Release Health updates, KB addendums or Known Issue Rollback notices that explicitly list storage regressions or offer mitigations. (bleepingcomputer.com)
Independent lab verifications and large‑sample reproductions that show a confirmed fix for known fail combinations. (tomshardware.com)
Any legal filings or public confirmations related to the forged internal advisory, which would validate Phison’s claim that the circulated document was not authentic.

Strengths, limitations and risk assessment

Strengths of the public evidence

Independent reproducibility: multiple enthusiasts and specialist outlets reproduced the same failure fingerprint under similar workloads, increasing the signal‑to‑noise ratio. (tomshardware.com)
Vendor acknowledgement: Phison publicly recognized it was investigating “industry‑wide effects,” which elevates this from forum chatter to an industry investigation. (wccftech.com)
Technical plausibility: the observed behavior matches known failure modes when host/driver changes interact badly with firmware, particularly in DRAM‑less/HMB designs. (windowsforum.com)

Limitations and outstanding unknowns

No single definitive public root cause yet: at the time of reporting, neither Microsoft nor Phison had released a complete forensic analysis tying the update to a specific kernel regression or firmware bug. Until telemetry is published, attribution remains a well‑supported hypothesis rather than proven. (bleepingcomputer.com)
Community lists are provisional: model lists circulating online are useful triage tools but not authoritative; firmware, capacity and platform variation matter.
Potential confounders: motherboard firmware, driver versions and even thermal behavior can change reproducibility, complicating rapid blanket statements about “all X controllers.”

Overall risk to the average user is moderate but the impact of a failure (data corruption or inaccessible drives) is high; that combination warrants conservative operational choices until vendors publish validated fixes.

Conclusion

The August 2025 Windows 11 cumulative update (KB5063878) has been linked by multiple independent test benches and specialist outlets to a reproducible storage regression that can make some NVMe SSDs disappear during sustained, large writes. Phison has publicly acknowledged it is investigating industry‑wide effects and is coordinating with partners; Microsoft is collecting telemetry and working with storage vendors to reproduce and analyze reports. The most likely remediation path will involve vendor firmware updates and, if needed, a Microsoft host mitigation.
Until vendors publish validated firmware and Microsoft provides conclusive guidance, the safe, pragmatic posture for both home users and administrators is straightforward: back up critical data immediately, avoid sustained large sequential writes on patched systems, stage the Windows update in pilot rings for production environments, and apply only vendor‑recommended firmware updates after backing up. Treat unauthenticated internal memos and sensational social claims as suspect; rely on official vendor advisories and Microsoft release‑health entries for final clearance. (tomshardware.com) (bleepingcomputer.com)

Source: TechPowerUp Phison Posts Latest Update on SSD Controller Stability

ChatGPT · Aug 27, 2025

Phison’s latest public stance changes the tone of what started as a panic: after industry-wide reports that a mid‑August Windows 11 cumulative update could cause NVMe SSDs to disappear during long writes, Phison says its internal testing — described as extensive — was unable to reproduce the catastrophic failures and it recommends heatsinks for high‑performance drives as a precautionary measure. d‑August, Microsoft released a combined Servicing Stack Update (SSU) and Latest Cumulative Update for Windows 11 (commonly tracked as KB5063878, with related preview packages like KB5062660 cited by community reports). Within days, independent testers and enthusiast labs published repeatable test cases showing that, during sustained sequential writes (commonly reproduced around the ~50 GB mark and often when drives were partially full), some NVMe SSDs stopped responding and vanished from Windows device inventories. The symptom set — device disappearance from File Explorer and Device Manager, unreadable SMART/controller telemetry, and occasional file truncation or partition corruption — suggested a controller‑level hang or firmware state corruption triggered by a host‑side behavior change.
The initial communia of drives equipped with Phison controllers and a number of DRAM‑less/HMB‑dependent modules. That pattern prompted Phison to publicly acknowledge an investigation and to work with partners, while Microsoft said it was “aware of” reports and was collecting telemetry through the Feedback Hub and support channels. Multiple independent outlets and labs reproduced the failure fingerprint, elevating the incident beyond isolated anecdotes.

What Phison actually said — the timeline and the claimtad been made aware of “industry‑wide effects” attributed to the Windows updates and said it was reviewing controllers that may have been involved and coordinating with partners. Days later, media reports summarized a follow‑up assertion from Phison that its lab work — described by outlets as more than 4,500 cumulative testing hours and over 2,200 test cycles on the drives reported as potentially impacted — failed to reproduce the reported issue. Phison also emphasized that no partner or customer reports had confirmed drives affected at scale at the time of that internal testing.

Two immediate takeaways from Phison’s messaging:

Phison acknowledged the investigation and engaged partrse for a controller‑level or cross‑stack issue.
Phison reported it could not reproduce the field failures in its test matrix during the reported test campaign, a claim that—if accurate—shifts the ministic controller bug to a more complex, interaction‑dependent problem or a potentially small, hard‑to‑reproduce subset.

A note on the “4,500 hours” figure

The numeric claim that Phison “ran 4,500 cumulative testing hours” appears in multiple media summaries, but public, primary test logiled Phison lab report were not published alongside that number at the time of reporting. Several technical analyses and forum consolidations specifically caution that such numerical claims should be treated as provisional until corroborated by a primary vendor test log or an independent lab report containing full test artifacts. In short: the claim exists in vendor‑summarized press coverage, but it was not verifiable from a publicly posted, audited test record at the time. That caveat is vital for IT decision‑makers and procurement teams.

What the independent reproductions found (technical profile)

Multiple outlets and community test benches converged on a consistent operational fingerprint:

Trigger profile: Sustai large archive extraction, cloning or copying tens of gigabytes in one continuous pass), often when the SSD was partially filled (~50–60% in many reproductions).
Symptom set: The NVMe device becomes unresponsive mid‑write, disappears from the OS (File Explorer, Device Manager, Disk Management), vendor utilities show unreadable SMART/controller telemetry, and files in flight can be truncated; in drive returned after reboot but sometimes remained inaccessible.
Susceptible hardware patterns: Community lists initially over‑represented Phison‑based controllers and some DRAM‑less/HMB‑dependent SSDs, though isolated cases involved other controllers as well — indicating a cross‑stack host/controller interaction rather gle‑vendor failure mode.

Those reproducible lab patterns are why the issue received rapid attention: repeatability across independent benches gives engineers concrete test recipes for forensic work and strengthens the case that this was not purely anecdotal noise.

Why this likely isn’t a simplell

The public evidence points to a behavioral interaction between the Windows storage stack and SSD controller firmware rather than wholesale hardware destruction. Key technical reasons:

The failure profile resembles a controller hang or firmware state corruption exposed by specific host timing and buffer allocation changes, rather than physical damage to NAND or controller silicon. In many cases drives became visible again after a reboot — inconsistent with physical bricking.
DRAM‑less controllers that use the NVMe Host Memory Buffer (HMB) are more sensitive to host allocation semantics; changes in how Windows allocates or sequences buffers can expose latent race conditions. Prior Windows 11 24H2 interactions had already exposed HMB‑related fragility on select models, mis plausible and consistent with observed behavior.
Community reproductions were specific: a particular sustained workload and drive fill level consistently triggered the issue. That kind of narrow fingerprint points to an interaction that is harder to trigger at random and therefore less likely to be a universal hardware recall scenario.

That said, *for affected usesult is the same as a bricked drive: inaccessible files and potential data loss until recovery steps or vendor interventions succeed. The practical risk is therefore high for a small subset of users even if the overall failure probability is low.

The forged advisory and misinformationusion, a falsified Phison advisory circulated on enthusiast channels and social feeds, listing affected controller IDs and advising specific mitigations. Phison publicly disowned that forged document and signaled potential legal action. The presence of a fake internal memo complicated triage and increased noise for partners and support desks, diverting attention away from engineering and forensic efforts. This incident is a case study in the real harm misinformation can cause during a technical crisis.

Phison’s precautionary advice: heatsinks and thermal considerations

Even though Phison reported it could not reproduce the reported failures, the company recommended that users employ proper heatsinks or thermal pads for high‑performance drives during extended workloads (large file transfers, archive extraction, and similar sustained writes). The stated rperature helps maintain optimal operating conditions, reduce thermal throttling, and ensure sustained performance.
Technical perspective on the heatsink recommendation:

What a heatsink does: reduces operating temperature and delays or reduces thermal throttling, helping maintain the controller’s performance under long sustained workloads.
What a heatsink does not do (necessarily): it is not a firmware fix. If the root assertion is that host timing changes trigger a controller firmware rata corruption, cooling alone may not prevent the specific failure mode.
Why Phison may recommend it anyway: high temperatures can exacerbate firmware stress paths and increase the chance of timing anomalies manifesting under load; recommending heatsinks is a low‑cost, broadly useful mitigation that reduces one variable in complex stress tests while vendors investigate code‑level fixes.

In short, heatsinks are good practice for high‑performance NVMe drives under heavy use, but they are a complementary mitigation rather than a guaranteed cure for a host/controller interaction bug.

Practical guidance for users and administrators (clear, prioritized)

Back up critical data immediately to a physically separate medium or a reliable cloud provider. Verified backups are the single most effective defense.
If KB5063878 (or related updates) is not yet installed on a machine that performs heavy sequential writes, consider postponing installation until vendors and Microsoft publi firmware advisories, or mitigations validated by independent labs.
If you already installed the updates:
Avoid large single‑pass transfers (> ~50 GB) on NVMe drives that may be at risk.
Break large operations into smallere or Microsoft guidance arrives.
Use vendor utilities to record model/firmware and take screenshots of Device Manager and SMART info for triage if needed.
Check SSD vendor support pages and management utilities (Corsair, WD, Samsung, Crucial, etc.) for firmly apply vendor‑recommended firmware after performing full backups. Firmware updates can carry their own risk and should be applied carefully.
For fleet owners and admins:
Hold the update in pilot rings and run representative sustained sequential write tests (50+ GB) across your inventory before broad deployment.
Ensure WSUS/Intune/MDor stage KB deployment where needed.

These steps reflect the consensus posture across independent labs, specialist outlets, and vendor guidance during the incident: conservative, data‑first, and staged.

Assessing Phison’s testing claim and the limits of lab redor says “we tested for X hours and couldn’t reproduce,” that’s an important signal — but not definitive proof of universal safety. Reasons why:

Test coverage vs. field diversity: SSD behavior can depend on firmware revision, NAND die/vendor, PCB power delivand platform BIOS/UEFI. A vendor lab may test many combinations, but it is extremely difficult to cover every OEM‑branded SKU and every platform permutation.
Workload sensitivity: the failure profile requires a very specific sustained workload and particular fill levels; if a lab’s test matrix doesn’t mirror the field trigger precisely (queue depth, command pacing, host memory timing, platform interrupts), the bug can remain elusive.
Reproducibility and timing: intermittent or timing‑sensitive edge cases often require exact environmental and timing reproduction; passing lab tests reduces the probability of widespread failure but does not 100% eliminate the possibility of rare, events.

Therefore, while Phison’s lab results are reassuring in that they didn’t reproduce the panicked scenarios at scale, they should be treated as one input into risk decisions — corroborating telemetry and independent lab reproductions remain essential.

The bigger lessing and the Windows ecosystem

This incident underscores structural realities in modern PC update ecosystems:

Co‑engineering fragility: OS updates interact with firmware, drivers, and hardware in subtle ways. Host timing or buffer allocation changes can expose latent controller ons. The surface area for these interactions is increasing as SSDs rely more on host cooperation features like HMB.
Staged rollouts matter: Staged deployments and diverse test rings that include heavy write workloads and DRAM‑less/HMB‑dependent configurations should be standard practice for enterprise and consumer channels alike.
Telemetry sharing and forensic protocols: Faster, structured telemetry exchanges between Microsoft and controller/drive vendors shorten diagnosis and reduce remedial latency. The industry needs better, privacy‑respectful telemetry tooling that can correlate OS logs with controller traces.
Misinformation is dangerous: Forged advisories deepen confusion and harm users and platforms must stamp out false artifacts rapidly to keep attention on engineering fixes.

Risks and where uncertainty remains

The exact cross‑product matrix that triggers permanent corruption versus a transieision + controller family + motherboard BIOS + CPU + memory timing + drive fill level) has not been published in a comprehensive, vendor‑validated matrix accessible to IT teams. That gap prolongs uncertainty.
Numerical test claims (e.g., “4,500 hours”) were reported by press outlets summarizinut primary test logs and lab artifacts were not widely published at the time — a notable transparency deficit for teams making mission‑critical decisions.
Some community reproductions implicated nonlated cases, so narrowing remediation to only one vendor risks missing other vulnerable combinations. Until vendors publish SKU‑level advisories, lists compiled by community testing should be treated as investigative leads, not definitive inventories.

Because of these gaps, prudent organizations should assume uncertainty and adopt defensive postures (backupd vigilant monitoring) until validated fixes and firmware changelogs with confirmed affected/non‑affected lists appear.

Conclusion — measured, practical takeaways

The episode started as a sharp, public concern — reproducible community tests showed drives ined writes after the Windows 11 update. Phison’s subsequent public testing response and inability to reproduce the field failures in its internal test campaign is an important data point and—together with Microsoft’s ongoing telemetry gathering—helps de‑escalate a universal “bricked drives” narrative. However, the risof users remained real while remedial steps were being developed.
What matters for readers and administrators is straightforward and enduring: maintain verified backups, stage updates where possible, avoid large uninterrupted write jobs on systems that received the implicated updates until vendor guidance arrives, and monitor vendor support advisories for firmware patches and validated remediation instructions. Phison’s advice to use heatsinks on high‑performance drives is sensible maintenance guidance, but it is not a substitutional fix for a host/controller interaction that may ultimately require firmware or OS‑level remediation.
This incident is a reminder that software updates and hardware firmware increasingly co‑depend, and that careful testing, better telemetry sharing, and conservative deployment practices are essential to reduce the chance that a narrow edge case turns into a high‑impact outage for users.

Source: Tom's Hardware Phison squashes reports of Windows 11 breaking SSDs — says it was unable to reproduce issues despite 4,500 hours of testing, recommends users deploy heatsinks just in case

ChatGPT · Aug 27, 2025

Phison says its lab work could not reproduce the Windows 11 SSD corruption reports that circulated after the August cumulative updates — but the episode exposes how fragile modern storage stacks can be when OS updates and controller firmware collide, and why backups, staged rollouts, and vendor telemetry remain the only reliable defenses against catastrophic data loss.

Background / Overview

Microsoft shipped the combined Servicing Stack Update (SSU) and Latest Cumulative Update for Windows 11 identified as KB5063878 on August 12, 2025. The public KB lists security and quality fixes and initially stated no known storage-related issues; within days, community test benches and independent outlets began reporting a reproducible failure profile where some drives would disappear under sustained, large sequential writes. (support.microsoft.com)
Independent testers and several outlets documented that the symptom generally appeared during continuous writes of tens of gigabytes — commonly reported around ~50 GB — and was more likely on drives that were moderately to heavily used (often cited as >50–60% full). The operational fingerprint — drive disappearing from File Explorer, Device Manager and Disk Management while SMART and vendor telemetry go unreadable — strongly suggests a controller- or firmware-level hang rather than a trivial file-system glitch. (tomshardware.com, bleepingcomputer.com)
Phison, a major NAND-controller supplier whose silicon is used across many consumer NVMe SSDs, publicly acknowledged it was investigating reports tied to KB5063878 and a related preview update KB5062660. Several specialist outlets subsequently reported that Phison had completed internal validation testing and issued a follow-up statement describing test cycles and results; that reporting — reproduced in the community press — forms the basis of the vendor-side claims under analysis here. (wccftech.com, tomshardware.com)

What Phison reported (the company's test summary)

According to the report circulated via specialist press and summarized by community outlets, Phison’s public follow-up said:

Phison was made aware of reports that KB5063878 and KB5062660 could impact certain storage devices, including drives using Phison controllers.
The company “dedicated over 4,500 cumulative testing hours” and executed more than 2,200 test cycles on the drives reported as potentially impacted.
After that testing, Phison stated it was unable to reproduce the reported issue, and that it had not received partner or customer reports indicating drives had been affected in their telemetry. The company emphasized continued monitoring and partner collaboration.

Two important editorial notes on that summary:

The phrasing and numbers above were reported and quoted by specialist outlets and community aggregators; a primary Phison press release containing the exact test-hour figures is not publicly discoverable through vendor press pages at the time of writing, so that specific numeric claim should be treated with caution until the company posts the full test report or an official statement on its own channels. (notebookcheck.net, wccftech.com)
Phison’s public posture — investigate, validate in-lab, coordinate with partners, and publish partner advisories if needed — is consistent with how controller vendors typically handle cross-vendor firmware/OS interactions; the crucial question is whether Phison’s validation matrix matched the real-world workload and hardware diversity seen in community reproductions. (bleepingcomputer.com, tomshardware.com)

How independent testing and community reports shaped the story

Reproducible symptom profile

Multiple independent test benches and hobbyist researchers converged on a narrow failure window: continuous sequential writes (bulk file copies, archive extraction, large game installs) approaching or exceeding roughly 50 GB to a target SSD that was already partially filled. Under those conditions, the target device would sometimes become unrecognizable to Windows mid-write, vendor utilities and SMART telemetry would become unreadable, and files written during the event would sometimes be truncated or corrupted. Reboots often restored visibility; in a minority of cases drives remained inaccessible. (tomshardware.com, notebookcheck.net)

Which hardware showed up most frequently

Early community collations over-represented drives using certain Phison controller families and DRAM-less designs that rely heavily on Host Memory Buffer (HMB). That over-representation is a signal, not proof of exclusive culpability: later reproductions implicated drives using other controllers as well, suggesting a host-to-controller interaction rather than a single-vendor firmware bug. Still, the plurality of reports mentioning Phison controllers was what prompted Phison’s public acknowledgement and partner coordination. (tomshardware.com, notebookcheck.net)

Geographic and scale notes

The earliest reproducible signals came from enthusiast communities and independent testers in Japan and elsewhere. While many tests produced consistent symptoms under a specific workload, large-scale telemetry from Microsoft and most OEMs did not initially show a broad increase in disk failure rates, which suggests the issue may be high-severity but low-prevalence — rare in occurrence, but severe when it hits. Microsoft asked affected customers to file Feedback Hub reports and to contact support to aid telemetry collection. (bleepingcomputer.com)

Technical anatomy — plausible mechanisms

Modern NVMe SSDs are co-engineered systems where the OS kernel, NVMe driver, controller firmware, NAND management, and any on-board DRAM or HMB interact continuously. The reported failure pattern points to a few plausible technical vectors:

Controller hang due to metadata or cache exhaustion: Sustained sequential writes, especially on drives that are >50–60% full, stress SLC cache windows and metadata pathways. Exhaustion of fast caches or pathologic handling of metadata updates under pressure can push firmware into an unrecoverable state.
Host Memory Buffer (HMB) timing/allocations on DRAM-less designs: DRAM‑less SSDs depend on host memory for certain operations. Changes in host allocation timing or buffer sizing (potentially introduced by an OS update) can expose firmware edge cases. Past Windows 11 rollouts have shown HMB-related fragility on some drives, which makes this a plausible vector. (notebookcheck.net)
NVMe command ordering or driver timing regressions: Small changes in how the host issues flushes, barriers, or queue management can interact unpredictably with specific firmware implementations, causing controller threads to deadlock or drop into unhandled error paths.
Thermal and sustained-workload stress: Although less likely to explain mid-write disappearances on otherwise healthy hardware, thermal throttling or overheating can exacerbate firmware timing and error recovery paths. Phison and several outlets advised using heatsinks for extended write workloads as a best practice.

All of these are plausible; the evidence from community labs favors a workload-dependent host-to-controller interaction as the root category, rather than a simple factory defect affecting a single SKU or batch.

Evaluating Phison’s test claims — strengths and questions

Phison’s reported test investment — the headline numbers of over 4,500 cumulative testing hours and more than 2,200 test cycles — if accurate, would represent substantial validation effort and a meaningful data point in favor of the vendor’s reliability posture. A thorough internal test program with thousands of test hours and repeated cycles is precisely how vendors stress reproduce and validate firmware fixes.
Strengths of Phison’s reported approach:

Scale of testing: Large cumulative hours and thousands of cycles imply repeated, systematic stress patterns across hardware variants and firmware revisions. That can catch many classes of faults.
Partner-led remediation path: Phison’s coordination with drive manufacturers (who integrate controller firmware into branded SKUs) is the correct operational model for shipping validated firmware updates and ensuring vendor-side compatibility tests. (wccftech.com)

Questions and limitations to flag:

Repro test coverage vs. real-world heterogeneity: Community reproductions reported a narrow workload trigger (e.g., 50 GB continuous writes on partially-filled drives). If Phison’s lab tests used different patterns, capacities, or platform topologies than those seen in the wild, a negative reproduce result does not conclusively rule out a real-world interaction.
Transparency of the test matrix: The specific drive models, firmware versions, host platforms, and exact test steps were not published in a publicly discoverable Phison bulletin at the time of reporting. Without that matrix, independent validation is limited and the community cannot verify that the same workload was attempted. This gap fuels uncertainty. (notebookcheck.net, tomshardware.com)
Unverified numeric claims: The precise numbers quoted in press summaries (4,500 hours, 2,200 cycles) were reported by outlets that cited Phison’s statement; a matching primary vendor PDF or press release containing those figures could not be located on Phison’s official press pages at the time of cross-checking, so those figures should be treated as vendor-reported and awaiting direct publication for confirmation. (notebookcheck.net)

In short: the vendor’s effort and intention appear credible and appropriate, but the lack of a detailed, public test matrix leaves open the possibility that corner-case real-world configurations were not executed in the same way during lab validation.

Best practices for end users right now

Phison and multiple specialist outlets converged on practical, conservative recommendations while the investigation continued. These are operational, low-cost actions that materially reduce risk:

Back up important data immediately — there is no substitute for up‑to‑date backups when low-level storage metadata is at risk. Keep at least one offline or offsite copy of critical data.
Avoid sustained large sequential writes on patched systems — split huge transfers into smaller batches (for example, under 10–20 GB per batch) until vendors confirm fixes. Community reproductions often used single-run writes of ~50 GB as the trigger. (tomshardware.com)
Delay or stage the KB5063878 deployment in production — IT administrators should hold the update in pilot rings and include representative storage hardware and real-world write workloads in staging tests. Use update deferral for fleet units that have at-risk SKUs. (support.microsoft.com)
Apply vendor firmware updates only after backing up — if an SSD vendor issues a firmware update, follow the vendor’s documented update procedure and keep backups in case of a firmware flash failure.
Enable hardware heatsinks or thermal pads for heavy workloads — Phison reiterated that sustained writes stress controllers thermally and recommended using heatsinks or thermal pads to maintain optimal operating temperatures for sustained workloads. While this is not a fix for a host/firmware interaction, it reduces thermal-related error vectors.
Report incidents to Microsoft and vendors — affected users should file Feedback Hub reports and contact vendor support so telemetry and logs can be collected for forensic analysis. Microsoft explicitly asked for customer reports to aid its investigation. (bleepingcomputer.com)

Guidance for system builders and IT administrators

Inventory: create a prioritized inventory of fleet devices that use SSDs with Phison controllers or DRAM‑less designs and flag units with >50% used capacity.
Pilot: run realistic, sustained-write workloads in a controlled pilot ring that mirrors production tasks — game installs, archive extraction, disk cloning, and bulk media transfers are sensible stress tests.
Staged rollout: delay broad deployment of KB5063878-derived packages to mission-critical systems until vendor guidance or Microsoft mitigations are available.
Telemetry: instrument affected machines to capture NVMe SMART, event logs, and any dump files for failed cases — preserve logs for vendor analysis.
Firmware policy: coordinate with SSD vendors for validated firmware updates and insist on vendor-provided release notes that specify which models and firmware revisions are addressed.

These steps convert a reactive posture into an operationally defensible one that reduces exposure while vendors and Microsoft complete forensic work.

Risks and what to watch next

Undisclosed edge cases: Without a published Phison test matrix and a Microsoft post‑mortem, hidden combinations of platform BIOS, driver versions, OEM firmware, and drive capacity could still trigger failures even after targeted vendor patches.
Misinformation and forged advisories: The incident saw forged documents circulate claiming internal bulletins and laundry lists of affected controllers. That noise complicates triage and may cause unnecessary alarm or improper mitigation. Treat only vendor-published advisories as authoritative.
Non-Phison exposure: Community tests implicated non-Phison drives in some reproductions; focusing solely on one vendor risks neglecting other vulnerable SKUs. Broad staging and telemetry remain essential. (notebookcheck.net)

Watch for these vendor signals:

Official Phison publication of the lab test matrix or a formal test report (drive models, firmware IDs, host platforms, exact reproduce steps).
SSD vendor advisories and firmware releases from the drive makers that integrate Phison controllers.
Microsoft release-health updates or targeted mitigations for KB5063878 (or subsequent out-of-band updates) that explicitly reference storage regressions and provide remediation paths.

Bottom line — measured verdict

Phison’s reported lab work and partner coordination are the right operational steps; large-scale validation testing is the proper, responsible response to cross-vendor issues. However, the episode underlines two sober truths for Windows users and administrators:

No single vendor statement — even one that reports thousands of test hours — is a definitive closure unless the test matrix and reproduce steps are published and independently validated against the community’s workload profile.
The practical defense against update-triggered storage regressions remains unchanged: proactive backups, representative staging rings, cautious update deployment, and timely vendor telemetry reporting.

Until vendors publish a detailed, verifiable post-mortem and validated firmware or OS mitigations are widely available, the safest operational posture is conservative: avoid single-run large writes on patched systems, maintain backups, and follow only official vendor and Microsoft guidance. (wccftech.com, bleepingcomputer.com)

Action checklist (for readers right now)

Back up critical files and system images immediately.
If your system received KB5063878 and you rely on NVMe SSDs for large writes, postpone non‑urgent large file transfers.
If you experience a disappearing drive mid-write, stop writing to the device, collect logs, and contact the SSD vendor and Microsoft Support; file a Feedback Hub report to help telemetry collection. (bleepingcomputer.com)
Check your SSD vendor’s support site for firmware advisories and only apply vendor-released firmware with a verified backup in place.
For system builders: add write-heavy stress tests (50+ GB single-run transfers) to your staging ring for any systems that will receive KB5063878.

Phison’s follow-up reporting — and community reproductions — have forced an important conversation about how OS updates interact with device firmware under sustained stress. The company’s lab work is an encouraging sign that the ecosystem is taking the problem seriously, but the lack of a fully transparent, published test matrix and the presence of conflicting community reproductions mean the situation is not yet resolved. Until vendors and Microsoft publish coordinated, verifiable fixes and forensic findings, defensive operational practices and diligent backups are the only reliable guarantee against becoming an unlucky statistic in this unfolding story. (support.microsoft.com, tomshardware.com)

Source: Neowin Phison releases test report on Windows 11 SSD corruption issue

ChatGPT · Aug 27, 2025

Phison’s lab says the recent Windows 11 cumulative update is not “breaking” SSDs — but the episode lays bare how fragile modern storage stacks can be, how quickly panic and misinformation spread, and why conservative update practices and strong backups remain non-negotiable.

Background / Overview

Microsoft shipped a combined Servicing Stack Update (SSU) and Latest Cumulative Update for Windows 11 (commonly tracked as KB5063878, OS Build 26100.4946) in mid‑August 2025. Within days, multiple independent community testers and specialist outlets published reproducible test cases in which certain NVMe SSDs became unresponsive — disappearing from File Explorer, Disk Management and Device Manager — during sustained, large sequential writes. The symptom set commonly described: a drive that “vanishes” mid‑transfer, unreadable SMART/controller telemetry, and in some instances partial file truncation or data corruption. These reports rapidly escalated into an industry investigation. Dose silicon is used across many consumer and OEM NVMe drives — publicly acknowledged it was investigating reports linked to the Windows update and said it was working with partners to identify potentially affected controller families. Shortly afterward the company said its own lab testing, which it characterized as extensive, was unable to reproduce the field failures; Phison reported running thousands of cumulative testing hours and multiple test cycles without seeing the reported disappearance behavior. That shift from “investigating industry‑wide effects” to “we couldn't reproduce it” is the center of this story.
Microsoft confirmed it was “aware of” cokend telemetry and feedback via standard channels while coordinating with storage partners. At the same time, independent reproductions remained available from enthusiast labs and outlets, making the situation appear contradictory: community tests showed a repeatable fingerprint while vendor labs reported no repro under their test matrices.

What the reports actually claimed

The community reproductions: a narrowns converged quickly on a common trigger profile:

Sustained sequential writes on the order of tens of gigabytes (commonly cited around 50 GB).
The target SSD often being partially filled (reports typically referenced drives at ~50–60% capacity).
Symptoms appearing during a continuous write workload such as a large archive extraction, cloning operation, or a big file transfer.
Outcomes ranging from temporary disappearance (restored by reboot) to drives that returned with unreadable telemetry or required vendor‑level recovery.

Enthusiast and specialist sites reproduced the failure fingerprint on test benches and published step‑by‑step recipes that otheee the reason vendors and Microsoft took notice quickly: repeatability raises the chances that this was a real host‑to‑controller interaction rather than random hardware failure.

The vendor position: Phison’s investigation and lab results

Phison first acknowledged the reports and said it was reviewing controller families that “may have been imt communicated to partners and press that its internal testing campaign — described in some coverage as more than 4,500 cumulative testing hours and over 2,200 test cycles on the reported drives — failed to reproduce the reported issue, and that no partners or customers had reported widespread impacts at the time of its tests. Phison also recommended thermal mitigation such as heatsinks for high‑performance modules as a general precaution.
It’s important to note that media summaries quoting the “4,500 hours” figure did so based on Phison’s statements in coverage; a primary, audited Phison test log was not publicly published alonirculated. That gap matters for forensic completeness and should temper how final that numeric claim sounds.

Technical anatomy: why a Windows update can expose SSD problems

To evaluate the claims and the vendor response, it helps to understand the key technical layers involved:

NVMe SSDs are embedded systems

An NVMe SSD is not it’s an embedded computer:

A controller (firmware) that manages channels, wear leveling, and error correction.
NAND flash organized in channels and blocks.
Optional on‑board DRAM used for mapping and caching, or Host Memory Buffer (HMB) in DRAM‑less drives, where the controller borrows host RAM for mapping tables.
A host OS NVMe driver and kernel I/O path that issue commands and allocate resources.

Because these elements are tightly coupled, small changes in host behavior — timing, memory allocation, or I/O queuing — can exercise latent controller firmware bugs. In prior Windows 11 24H2 interactions, Host Memory Buffer allocation behavior previously exposed issues in DRAM‑less designs, establishing precedent for a host‑driven regression.

Common failure mechanisms consistent with the reported fingerprint

Controller hang / firmware state lock: If the controller enters an unexpected state, it may stop responding to NVMe admin commands. From the OS perspective, the device can appearrThe unreadable SMART/telemetry reported by testers is consistent with a controller-level lock that prevents normal queries.
SLC cache depletion and metadata pressure: Sustained sequential writes can exhaust SLC caching on consumer drives, forcing more complex write patterns and heavier internal metadata updates. If a controller’s firmware has an edge-case bug under those conditions, behavior can be unpredictable.
iming or allocation changes (HMB)**: DRAM‑less SSDs rely on predictable host HMB behavior. If an OS update changes how HMB is used, the controller may see different timing or memory patterns that it wasn’t widely tested against.
Thermal throttling and heat: Large transfers generate heat. Therift controller timing behavior; in marginal cooling scenarios, heat can precipitate instability in stressed firmware states. Phison explicitly noted heat as a plausible contributing factor and recommended cooling.

These mechanisms are not mutually exclof HMB behavior, SLC cache exhaustion, and thermal stress under sustained large writes can collude to expose rare firmware race conditions.

Cross‑checking the claims: what’s verified and what remains unproven

Verified: Microsoft released KB5063878 as a Windows 11 cumulative update and communited reproducible failure profiles under heavy sequential writes. Multiple specialist outlets aggregated those community reproductions.
Verified: Phison publicly acknowledged an investigation and later reported it could not reproduce the field failures in its internal testing campaign. The company recommended standard thermal precautions and said it was coordinating with partners.
Unproven / cautionary: The precise root cause across all reported incidents — whether a specific Windows change, a particular controre versions, or a unique assembly of host factors — has not been published as a single, vendor‑verified post‑mortem at the time of the reporting in these files. Community model lists of “affected” drives are provisional investigative leads and not defin ble test cases exist, vendor labs reported no repro, and a final, public forensic tie between host telemetry and controller logs was not available in the public record summarized here.
Unverified numeric detail: The exact composition of Phison’s “4,500 cumulative testing hours / 2,200 test cycles” figure lacks a published, audited log in the public reporting we have; treat the number as a vendor‑reported assertion pending primary test artifacts.

The information ecosystem problem: forged advisories and panic

This incident wasn’t purely technical — it also illustrated how misinformation amplifies risk. A forged internal‑style advisory circung blanket catastrophic failure for Phison drives. Phison publicly denounced the document as fake and signaled intent to pursue legal action against distributors of the forged material. The fake memo had operational impacts: it confused partners, accelerated panic, and conflating community‑sourced lists with vendor‑validated telemetry. That episode underscores a critical challenge for the PC ecosystem: verified vendor communications matter, and unverified internal documents can cause real damage.

Practical guidance: what users, enthusiasts, and IT teams should do now

The situation described a narrow, workload‑dependent failure profile that is real enough to warrant pragmatic precautions. Recommended actions are straightforward and prioritized by risk:

For consumers and enthusiasts

Back up immediately — This is first and non‑negotiable. If you store irreplaceable data locally, ensure a verified backup exists before running heavy write workloads or applying updates.
Avoid sustained large sequential ated systems — Delay massive file transfers, archive extractions, cloning jobs, or reinstallations on systems that installed KB5063878 until you confirm vendor guidance or have validated the behavior on your hardware.
Check SSD firmware and vendor utilities — Use manufacturer tools (Corsair iCUE, SanDisk Dashboard, WD Dashboard, etc.) to confirm firmware versions and follow any vendor advisories. Vendors are the distribution channel for controller firmware fixes.
Monitor for ffficial advisories — Don’t rely on forum lists; wait for vendor‑published firmware updates and validated release notes. Apply firmware updates only after you have backups.

For system builders and IT administrators

Stage updates in representative test rings that include hed the actual set of storage hardware used in production. Don’t assume a cumulative update is zero‑risk for specialized workloads.
Create rollback and emergency recovery playbooks for storage incidents and ensure imaging tools and backups are regularly vale telemetry collection for affected endpoints: gather event logs, NVMe driver traces, and vendor diagnostics when investigating a disappearing drive. Share sanitized telemetry with vendors so they can correlate host

What vendors and platform owners can do better

Publish reproducible test artifacts where possible: When a vendor cites multi‑thousand‑hour test campaigns, publishing a high‑level summary of methodology and test coverage (or even redacted logs) The absence of primary test artifacts around the “4,500 hours” claim was noted and should be remedied in future incidents.
Improve pon: Shared stress test suites for host/storage interactions would help catch workload‑dependent regressions before broad rollout. Microsoft and controller vendors should expand cross‑stack sample test suites to include heavy sequential writes on a dectures (DRAM‑less, HMB, DRAM‑full).
Faster, clearer communication: Verified vendor advisories distributed through official channels minimize the harm done by forged documents and rumor. When in doubt, clear, frequent status updates reduce panic and unnecessary RMAs.

Strengths and weaknesses of the current reporting and responses

Strengths

Rapid community triage: Enthusiast tlets reproduced a consistent failure fingerprint quickly, which brought the issue to vendor attention faster than isolated anecdotes could have. The repeatability across multiple benches is a genuine strength of the community ecosystem.
Vendor engagement: Both Microsoft and Phison engaged and requested telemetry from affected users ande correct operational posture for a potential host‑to‑controller regression.

Weaknesses and risks

Incomplete public forensic disclosure: The lack of a publicly published, vendor‑audited test log for Phison’s reported test camncy gap and allowed speculation to flourish. Numerical claims without accessible methodology reduce trust.
Misinformation risk: The forged advisory and rapid spread of unverified model lists caused confusion and unnecessary alarm, illustrating how fragile public trust can be during incidents.
Fragmented ecosystem complexity: The diversity of SSD controller families, firmwaremblies, and platform firmware (BIOS/UEFI) means a single fix can require coordination across many parties — slowing remediation. That complexity increases the chance that some edge cases will be missed in p---

Where we stand and what to watch next

Expect firmware advisories and vendor utilities to be the primary delivery mechanism for any controller fixes. Watch for vendor release notes that name specific controller families and firmware versions.
Microsoft’s Release Health and KB aces to watch for official Known Issue entries or mitigations if the company decides an OS‑level rollback or patch is required.
Independent labs publishing controlled reproductions with exactatform details, and logs will be decisive in confirming whether the issue was host‑initiated, controller firmware, or a complex interaction. When such artifacts appear, they will clarify the true scope.

Final assessment: relief coupled with sober caution

Phison’s statement that its extensive in‑house testing could not reprodrive behavior is a welcome development; it reduces the probability that a broad, systematic controller flaw is being distributed through consumer drives at scale. That said, community reproductions and the initial symptom fingerprint are real and must be l they are reconciled with vendor and Microsoft telemetry.
This incident is a reminder of three core truths for anyone who depends on local storage:

Backups are non‑negotiable. Thedge against software regressions, firmware bugs, and human error.
Patch management should be staged for representative hardware. Test rings that mimic real‑world storage usage are essential for enterprises and enthusiasts who run heavy workloads.
Transparent, vendor‑verifie. Verified vendor advisories and published test artifacts reduce panic, minimize misinformation, and speed recovery.

Phison’s lab results are reassuring, but they do not erase the earlier reproductions or the lived experiences of users who reported distressing failures. The prudent posture for consumers and IT teams is cautious: keep backups current, postpone large write workloads on recently updated machines until firmware guidance is available, and apply vendor firmware updates only after you have verified backups and a clear remediation path. The ecosystem response to this incident — improved cross‑vendor test suites, clearer communications, and stronger telemetry sharing — will determine wheth compatibility scare or a more serious lesson in co‑engineering and rollout discipline.

Checklist: Immediate steps (quick reference)

Back up important data now.
If you’ve nd own an NVMe SSD, avoid large, continuous transfers (50 GB+).
Check your SSD’s firmware version with the vendor utility and follow official advisories.
Use heatsinks or ensure adequate case airflow for high‑performance NVMe modules as a thermal precaution.
For enterprise fleets: stage the update, run heavy‑write validation tests, and collect detailed telemetry for any anomalies.

The big picture: this episode is a victory for rapid community vigilance and vendor responsiveness, but it’s also a cautionary tale about complexity, transparency and the continued necessity of conservative, well‑tested update practices.

Source: xda-developers.com No, the latest Windows 11 update doesn't break SSDs, says Phison

ChatGPT · Aug 27, 2025

Phison’s latest test summary puts the disputed SSD failures tied to Windows 11 updates into a new, uneasy middle ground: vendors and Microsoft say they cannot reproduce a widespread “bricking” problem, while a small but alarming set of user reports continues to describe drives disappearing and in some cases becoming unrecoverable after installing KB5063878 and the KB5062660 preview update.

Background

Reports began surfacing in mid‑August when community testers and hobbyist PC builders posted that certain NVMe SSDs would vanish from Windows during sustained heavy writes — typically when drives were more than about 60% full and subjected to continuous transfers on the order of ~50 GB or more. Initial signal posts singled out SSDs using Phison NAND controllers as being disproportionately observed in failing systems, though a variety of models and controllers also appeared in early lists of affected hardware.
Within days, Microsoft acknowledged it was aware of reports and asked affected customers to submit Feedback Hub reports with diagnostic details. Phison — a major NAND controller supplier that powers a huge portion of consumer and OEM SSDs — publicly announced it had begun an investigation and later published a short validation summary saying it “was unable to reproduce the reported issue” after dedicating extensive test time to the problem. In that statement Phison reported more than 4,500 cumulative testing hours across roughly 2,200 test cycles, and encouraged end users to practice thermal management for drives under heavy sustained workloads.
The situation has since split the technical narrative: user-facing testers and some independent labs continue to claim reproducible failure modes under specific conditions, while large vendors and Redmond’s internal telemetry indicate no sign of a widespread fault. That split is exactly the reason this story matters — it exposes the friction between telemetry-driven vendor diagnostics and the messy, real‑world reproducibility demands of storage hardware under extreme IO patterns.

What the reports actually describe

Symptoms reported by community testers

Drives disappearing from Device Manager and the OS during or immediately after large, sustained write operations.
In some cases the SSD would reappear after a reboot; in other cases the device remained inaccessible and required low-level vendor tools or RMA to recover.
Problems were most consistently reported when a drive was over ~60% full and the write pattern involved tens of gigabytes of continuous data.
Affected devices included models from multiple brands, but many of the early, high‑visibility reports involved drives that use Phison controllers — including some DRAM‑less consumer NVMe parts.

These are user‑reported conditions, often derived from self‑tests using workload generators or real‑world large file operations (game installs, large archive extraction, etc.). They are credible as anecdotal evidence, but anecdote is not the same as statistically significant failure telemetry across millions of devices.

What vendors and Microsoft report

Microsoft’s internal testing and telemetry teams report they were unable to reproduce a systemic increase in disk failures or file corruption tied to the updates.
Phison’s validation report states more than 4,500 hours of cumulative testing across ~2,200 cycles focused on drives that were claimed to be affected; Phison reported no corruption or data loss reproduced in that testing.
Neither Phison nor Microsoft reported any widespread RMA spike that would indicate a large-scale failure wave.

The vendor positions are not unusual: when a small subset of devices shows an edge case failure pattern, industrial testing that doesn’t replicate the exact environmental or workload conditions can frequently come up negative. That does not automatically exonerate the update — it simply shows the challenge of reproducing rare combinations of hardware, firmware, OS state, and workload.

Why reproducibility matters — and why it’s hard here

Storage hardware is complex: performance and reliability depend on controller firmware, NAND flash behavior, thermal environment, system drivers, OS IO stacks, BIOS/UEFI firmware, and workload profile. When a problem only appears under specific conditions — for example, when the drive is partially full and under sustained writes that trigger certain internal caching or garbage‑collection states — reproducing it requires the exact combination of:

The same controller and NAND revision,
The same firmware version,
Matching drive fill percentage and logical layout,
The same OS build and update footprint,
Identical workload pattern and queue depth,
Similar thermal conditions (heatsink vs open M.2 slot),
The same system chipset and storage driver stack.

Small differences in any of these variables can make a fault appear or disappear. That explains how community testers can create a consistent failure profile on a handful of SSDs while major vendors’ lab cycles — even when extensive — can fail to observe the same behavior.

Phison’s validation: what they said and what it means

Phison’s public summary is terse but notable for two explicit claims:

They executed over 4,500 cumulative validation testing hours and more than 2,200 test cycles targeting the reported scenarios.
In those tests, Phison stated they were unable to reproduce the reported issue and that partners/customers had not reported drives being affected at scale.

The practical implication: Phison did not find an obvious firmware bug or deterministic controller failure that manifests on the workloads they chose to examine. That should reassure many users, particularly because Phison is a large controller supplier with incentive to identify quality issues. However, the statement is not a categorical proof the update could not possibly interact with certain rare hardware/firmware combinations to cause corruption.
Two technical caveats are important:

“Unable to reproduce” is not the same as “proven safe.” It means Phison’s lab conditions — including chosen test rigs, NAND batches, and settings — did not trigger the failure modes reported by users.
Phison’s monitoring of partners and customers found no widespread reports. That reduces the likelihood of a large‑scale OEM impact, but it does not eliminate the possibility of isolated batches or corner‑case firmware/NAND permutations.

Phison also advised end users to ensure proper thermal management (heatsinks or pads) during prolonged workloads. That is sound operational advice, but it also hints at an awareness that thermal conditions could exacerbate otherwise rare controller behavior.

How credible are the original tester reports?

Several independent outlets and community testers posted step‑by‑step reproductions that appeared credible: detailed hardware lists, drive fill percentages, and exact file sizes used in tests. Some testers documented partial recoveries after reboot and one tester reported an unrecoverable WD drive.
Those accounts are technically plausible: sustained writes on a drive that is more than 60% full will push the controller into more aggressive garbage‑collection pathways and increase thermal load. DRAM‑less designs or older controller firmware can be more vulnerable to transient performance or stability anomalies under such stress.
But from a journalistically rigorous perspective, the evidence is still limited:

The sample sizes in public tests are small (dozens, not thousands), and biased toward enthusiast hardware and configurations.
Tester environments are heterogeneous and often lack the low‑level telemetry vendors can produce.
There is not yet a reproducible, vendor‑verified test case that reliably fails across a broad set of hardware when the exact steps are executed.

Given those limitations, the claim that the Windows updates “brick” drives en masse is not supported. The claim that certain combinations of update + hardware + workload may lead to device disappearance or data corruption remains plausible and requires continued investigation.

Technical analysis: potential root causes and plausible mechanisms

While no vendor has pointed to a single confirmed root cause, several technical mechanisms could plausibly explain the reported symptoms:

OS buffer/memory leak interacting with storage cache: If the update modified or interacted with a kernel IO path in a way that stressed the OS‑buffered region (or the handling of flush commands), some controllers might face burst patterns or timing changes that expose firmware bugs.
Controller firmware corner cases: Many controllers include complex logic for wear leveling, background GC, and power‑loss protection. Rare state transitions — triggered by specific queue depths and sustained write patterns when the drive is partially full — can expose latent firmware bugs.
Thermal‑induced instability: High thermal load during sustained writes may cause performance throttling or transient behavior that complicates firmware timing, potentially leading to temporary disconnection or unrecoverable states.
Driver/OS changes to NVMe command timing: Windows updates occasionally change driver or stack behavior in ways that alter NVMe command timing or queue usage, possibly surfacing controller race conditions.

None of these mechanisms is proof of a systemic flaw. They are plausible engineering explanations that warrant targeted reproduction attempts.

Practical risk assessment for end users

Risk to the majority of users: Low. Vendor telemetry and large‑scale reporting so far do not indicate a mass‑market failure cascade.
Risk to specific configurations: Non‑zero. Enthusiast rigs, older firmware, DRAM‑less drives, or drives operating at high fill levels under heavy sustained writes could be more exposed.
Risk to data integrity: Significant if users are performing heavy writes without backups. Even a single unrecoverable SSD failure is a serious data loss event for the affected user.

Given the asymmetric cost of data loss versus the low probability of failure for most users, caution is the rational posture until vendors can definitively reproduce and remediate any specific bug.

Actionable advice: what users should do now

Backup immediately.
Maintain a current backup of any important data on all systems before applying updates or running heavy IO workloads.
Delay large sustained writes on systems running the August Windows updates (KB5063878 / KB5062660) if you use older or budget SSDs.
Avoid large game installs, disk cloning, or multi‑terabyte transfers in one pass until the issue is fully understood.
Keep firmware and drivers up to date.
Check your SSD vendor’s support site for firmware updates. Vendors sometimes roll out firmware fixes when a pattern emerges.
Use vendor diagnostic tools if a drive disappears.
Do not immediately reinitialize or repartition an inaccessible drive; first use manufacturer tools or seek support to attempt safe recovery.
Consider thermal improvements for NVMe drives.
Use an M.2 heatsink or thermal pad, particularly for drives in enclosed cases or high‑performance workloads.
Report detailed feedback to Microsoft and your drive vendor.
Use Feedback Hub and vendor support portals to provide logs and reproduction steps if you experience the problem.

These steps are conservative and pragmatic: preserving data integrity is the priority while the ecosystem works toward a technical resolution.

What vendors and Microsoft should (and appear to be) doing

Reproduce the exact failure pattern reported by testers using identical hardware, specific NAND batches, firmware versions, and thermal conditions.
Share a reproducible test case with partners publicly so other labs and OEMs can validate or refute findings.
If a root cause is identified in firmware, issue vendor firmware updates and coordinate with OEMs for distribution.
If the problem is traced to an OS change, Microsoft should publish a targeted mitigation or update to the affected code path and provide a KB article explaining the risk and mitigations.
Improve telemetry and feedback loop transparency so that independent testers and users can better understand whether their reports match vendor‑side findings.

At the time of reporting, Microsoft had asked for customer feedback and Phison had said it would continue monitoring and collaborating with partners. That approach is correct, but transparency about what exact test parameters were used would reduce public anxiety.

Strengths and potential weaknesses of the current handling

Strengths

Vendors and Microsoft responded quickly to user reports, which prevented the issue from being dismissed as purely rumor.
Phison invested significant engineering time (thousands of test hours) to investigate, which is a nontrivial commitment of resources.
Microsoft solicited targeted feedback and is coordinating with storage partners — an appropriate escalation path.

Weaknesses / risks

Public messaging is sparse and leaves a gap between vendors’ lab conclusions and the community’s experiences. Sparse statements can look like denial rather than careful technical evaluation.
Lack of a public, reproducible test case prevents independent labs and enthusiasts from converging on a consensus about what triggers the failure.
If the issue is tied to a narrow set of firmware/NAND permutations, affected users could be left without clear remediation paths or timely firmware updates from every OEM.

Final assessment

Phison’s statement that it “was unable to reproduce the reported issue” after thousands of hours of testing is important and reduces the likelihood of a broad, systemic failure affecting millions of drives. That should reassure most Windows users.
However, the combination of credible community reports, plausible technical failure mechanisms, and the severe consequences of single‑device data loss means the situation should not be dismissed. There remains a credible, albeit limited, risk that specific drive firmware + NAND batches, running under particular thermal and fill‑level conditions, could interact with Windows update changes in a way that produces drive disappearance or corruption.
Until a reproducible case is published or vendors issue targeted firmware/driver mitigations, the sensible course for users is simple: back up, avoid heavy sustained writes on potentially vulnerable drives, and keep firmware and drivers updated.

Conclusion

This episode is a reminder of how fragile the intersection of firmware, flash media, and operating system changes can be. Large vendors’ lab testing carries weight, but real‑world edge cases — those that span many small variables — can still hurt individual users. Phison’s inability to reproduce the failure after extensive testing is a positive sign, but it is not a final exoneration of all possible configurations.
Until vendors, Microsoft, and independent labs converge on a shared, reproducible cause (or conclusively prove there is none), the story remains unresolved at the margins. The responsible course for end users is to assume risk is possible and to act accordingly: back up, be cautious with large file operations on drives that are more than half full, and apply vendor guidance on firmware and thermal management. The community can hope for a clear technical post‑mortem; until then, prudence is the best protection against data loss.

Source: Windows Report Phison says it "failed to reproduce" SSD failure issue triggered by KB5063878 and KB5062660

ChatGPT · Aug 27, 2025

Windows 11’s August servicing wave briefly looked like a storage disaster: community testers reported NVMe drives disappearing mid-write after installing security updates KB5063878 and KB5062660, and many fingers pointed at SSDs using Phison controllers. After an industry investigation, controller maker Phison published a terse validation summary saying it had “dedicated over 4,500 cumulative testing hours” and run more than 2,200 test cycles without being able to reproduce the reported failures — and reported no partner or customer RMAs tied to the update at the time of its tests. That statement — and its caveats — has shifted the story from an apparent mass “bricking” to a complex cross‑stack compatibility incident that underlines how fragile OS, driver, firmware, and hardware interactions can be under heavy write workloads. (neowin.net)

Background / Overview

Windows 11 cumulative security packages released in mid‑August (commonly tracked as KB5063878, with a related preview KB5062660) were intended as routine security and quality fixes for 24H2 systems. Within days, independent testers and hobbyist builders published reproducible failure profiles: during sustained large sequential writes — often around 50 GB or more and typically on drives that were already substantially used — some NVMe SSDs stopped responding, vanished from Device Manager and File Explorer, and in a minority of cases returned corrupted or inaccessible data. Multiple community test runs and specialist outlets documented the pattern, with early collations showing a disproportionate number of affected units using Phison controller families. (tomshardware.com) (bleepingcomputer.com)
Microsoft acknowledged it was aware of the reports and asked affected users to provide feedback and logs while working with vendors to reproduce and diagnose the issue. Phison confirmed it was investigating and later issued a follow‑up message summarizing its lab validation efforts and advising standard thermal best practices for high‑performance SSDs. (bleepingcomputer.com, neowin.net)

The observed failure pattern — what community testing found

Multiple independent test benches converged on a consistent operational fingerprint that made the reports technically credible and urgent:

Drives often disappeared from Windows during or immediately after large, sustained write operations (game installs, large archive extraction, cloning, etc.). (tomshardware.com)
The symptom most commonly reproduced when the target SSD was already partially full (roughly 50–60% used) and after continuous writes on the order of ~50 GB. (tomshardware.com, windowscentral.com)
In many cases a reboot temporarily restored the device; in a smaller subset the device remained inaccessible until vendor tools, firmware reflashes, or RMA procedures were used. (tomshardware.com, bleepingcomputer.com)
A disproportionate number of early reports involved drives built around Phison controllers — particularly certain PS5012‑E12 family parts and DRAM‑less/HMB‑reliant modules — though other controllers were also reported in isolated incidents. (tomshardware.com, wccftech.com)

Those empirical reproductions matter: they produced a narrow, realistic workload profile that could be repeatedly triggered on some rigs, which pushed the issue from rumor to triage.

Phison’s investigation and the “4,500 hours” claim — what they actually said

Phison publicly confirmed it had been made aware of “industry‑wide effects” associated with KB5063878 and KB5062660 and said it would work with Microsoft and its partners to investigate. In media briefings and follow‑ups, Phison reported it had run an extensive internal validation effort, summarizing the campaign with the figures “over 4,500 cumulative testing hours” and “more than 2,200 test cycles,” and concluded it was unable to reproduce the reported failures in its laboratory testing. The company also noted that no partners or customers had reported drives being affected at scale in their telemetry during the investigation window. (neowin.net, wccftech.com)
Important caution: multiple independent summaries and community analyses flagged the numeric claim as a vendor‑reported summary rather than a published primary test log. In other words, the 4,500‑hour figure appears in Phison’s communicated summary and press reporting, but a fully auditable lab report or public test artifacts were not posted alongside that headline figure at the time of reporting; treat that numeric detail as asserted by the vendor pending publication of raw logs.
Phison’s practical guidance to end users emphasized thermal mitigation — adding a heatsink or thermal pad for extended workloads — and recommended partners stage firmware updates via the established vendor channels rather than direct consumer firmware pushes. That advice aligns with a plausible contributing factor: sustained writes generate heat, and marginal cooling can compound latent firmware timing or metadata issues under stress. (neowin.net)

Microsoft’s posture and telemetry

Microsoft publicly said it was “aware of” the reports and requested diagnostic submissions and Feedback Hub logs from affected users. Initial Microsoft telemetry reported no clear, large‑scale spike in drive failures tied to the update, which is why the vendor‑side lab results (and Phison’s validations) found no easy reproduction in controlled testing. However, Microsoft continued to collect field data while coordinating with SSD vendors and platform partners to correlate host telemetry with controller traces. That coordinated telemetry exchange is exactly what’s needed to convert a credible community failure profile into a verified root cause. (bleepingcomputer.com, tomshardware.com)

Why these failures are hard to reproduce in a lab

Reproducibility is the heart of this episode’s technical ambiguity. There are multiple interacting variables that can make a fault appear only in narrow conditions:

Controller firmware revision, NAND packaging, and on‑board DRAM vs. HMB allocation differences can change behavior under sustained writes.
Drive fill percentage matters because SLC caching behavior and garbage‑collection metadata pressure can shift when an SSD is partially filled versus empty. Sustained writes that deplete SLC cache force different internal write amplification and mapping activity.
Host OS build, NVMe driver timing, and any OS‑level changes to Host Memory Buffer (HMB) allocation can alter controller‑host interaction windows — small timing shifts can flip a latent race condition into a hard fault. Prior Windows 11 interactions have shown HMB timing fragility for DRAM‑less designs.
Thermal environment, heatsink presence (or absence), motherboard BIOS versions, and platform power delivery each influence whether a stressed controller crosses a stability threshold.

Because the issue appears to be an interaction across these layers, a vendor lab with a different set of motherboards, BIOS revisions, or ambient thermal conditions can easily run thousands of hours of tests and never trigger the same failure seen in a particular user’s rig.

Technical anatomy — plausible mechanisms (what engineers are looking at)

HMB and DRAM‑less controllers

Some consumer SSDs use Host Memory Buffer (HMB) instead of on‑board DRAM to store mapping tables. HMB relies on the OS and driver allocating predictable host memory. If an OS update changes HMB allocation timing, size, or access patterns, a controller expecting previous behavior might experience mapping inconsistencies or unexpected timing that could manifest as a hang. DRAM‑less designs are particularly sensitive to host timing changes.

SLC cache exhaustion and metadata pressure

When a drive receives sustained sequential writes, it initially uses fast SLC cache to absorb bursts. As the cache saturates — especially on drives that are already 50%–60% full — internal background tasks (garbage collection, wear‑leveling, metadata updates) intensify. If the controller firmware has an edge‑case under such metadata pressure, the controller could enter a non‑responsive state, making the device appear removed to the host.

Thermal and power effects

Large transfers heat components. Without adequate cooling (heatsinks, proper airflow), temperature rise can alter silicon timing margins, increase error rates, or provoke firmware timeouts. Phison explicitly called out thermal mitigation as an industry best practice for sustained workloads. Power delivery fluctuations or marginal PSUs can also change PCIe link stability during heavy IO bursts. (neowin.net)

Platform/BIOS and driver interactions

Motherboard firmware (UEFI/BIOS) versions and chipset NVMe drivers are a core variable. Some early reproductions pointed to combinations of specific motherboard models and BIOS revisions that made an issue reproducible in that environment but not another. That again explains why large‑scale lab testing without precisely matching platform conditions may not reproduce the problem.

Practical guidance — what Windows users and administrators should do now

The incident is an urgent reminder of basic, effective risk management for storage devices. Recommendations follow a simple priority order: protect data first, diagnose second, and remediate via vendor channels.

Back up critical data immediately. Use a verified external backup or cloud copy before running large writes or applying further updates. Backups remain the single best defense against data loss.
Avoid large, sustained write operations on systems that installed KB5063878 or KB5062660 until you confirm your SSD vendor has validated your firmware with the Windows update. Suspend game installs, large archive extraction, disk cloning, and media transfers >50 GB as a precaution. (tomshardware.com)
Identify your SSD controller and firmware. Use vendor utilities (WD Dashboard, Samsung Magician, Crucial Storage Executive, Corsair iCUE, etc.) or identify the controller via tools like CrystalDiskInfo/Device Manager. Document model, controller ID, and firmware version.
For fleet owners and IT admins: stage KB5063878 in pilot rings that include representative heavy‑write workloads and DRAM‑less designs. Run sustained sequential write stress tests (50+ GB) across your representative SKUs and firmware versions before broad deployment. Use WSUS/Intune to pause or defer the update for vulnerable groups.
Keep vendor firmware tools at hand; apply firmware updates only after verifying backups and reading vendor advisories. Firmware updates must be distributed through SSD manufacturers rather than relying on third‑party or leaked advisories. (wccftech.com)
If a device fails during a transfer: stop further writes, collect Event Viewer logs and vendor diagnostic output, image the drive (bit‑for‑bit) before attempting repair, and contact vendor support for RMA procedures. Preserving logs and a forensic image helps vendors correlate host traces with controller telemetry.

Practical hardware advice: for NVMe modules used for heavy workloads, mount a proper heatsink or ensure good airflow. Phison’s advisory specifically recommended heatsinks or thermal pads for sustained workloads to maintain optimal operating temperatures and reduce thermal throttling risk. (neowin.net)

Risk assessment — strengths in the vendor response and lingering weaknesses

Strengths:

Rapid acknowledgment and coordinated investigation among Microsoft, Phison, and OEMs reduced the window of uncertainty and prioritized forensic triage. (bleepingcomputer.com, wccftech.com)
Independent community reproductions provided detailed, repeatable test recipes that vendors could use to attempt repros — a constructive example of community + vendor collaboration. (tomshardware.com)

Weaknesses and open risks:

No single, publicly available vendor post‑mortem with correlated telemetry and controller traces had been released at the time of initial reporting; that absence leaves room for speculation. Multiple analyses urged the publication of primary test logs and forensic traces to close the loop.
The published “4,500 cumulative testing hours” figure is a vendor‑reported summary without immediate public test artifacts, so the numeric claim should be treated as provisional until Phison or partners publish detailed logs.
Firmware distribution models — where controller vendors deliver updates to drive makers who then push firmware to consumers — slow remediation versus a single unified patch channel. This creates uneven windows of exposure across mixed fleets.

Broader implications for Windows servicing and the storage ecosystem

This episode is not only a technical incident but a process one. Modern SSD architectures increasingly depend on co‑engineering between OS kernel behavior and controller firmware (HMB, timing assumptions, NVMe features). The following systemic actions would reduce recurrence risk:

Expand update test rings to include heavy sequential write workloads, DRAM‑less/HMB designs, and a representative matrix of consumer SSD firmware.
Improve structured telemetry exchange between OS vendors and controller manufacturers so field signals are correlated to controller traces quickly and with standardized formats. Faster forensic exchanges shorten remediation windows.
Encourage SSD vendors to publish transparent test artifacts when numeric claims shape public policy or procurement decisions; publishability builds confidence and helps third‑party labs validate fixes.

Final analysis — what this means for Windows users and the marketplace

The worst‑case headlines — that a Windows 11 update “bricked” all Phison SSDs — proved to overreach the evidence. The situation instead exposed a narrowly reproducible, workload‑dependent failure cluster that required careful cross‑stack forensic work to diagnose. Phison’s statement that it could not reproduce failures in its lab after an extensive test campaign should reassure many users; however, the vendor‑reported numbers need primary artifact publication for full verification and independent validation. In parallel, the reproductions from community labs and specialist outlets underscore that the problem was real in certain configurations and therefore worth taking seriously. (neowin.net, tomshardware.com)
For everyday users the bottom line is simple: back up, avoid large sustained writes on recently patched systems, and follow vendor guidance for firmware and thermal management. For IT teams and vendors, the incident is a practical call to invest in representative hardware test matrices, faster telemetry sharing, and clearer public communication when numeric testing claims shape public trust. Until vendors publish a full post‑mortem with correlated traces and validated fixes, a conservative, backup‑first posture remains the most pragmatic defense.

The episode closes with a modest but critical lesson: operating‑system updates fix many issues but can also expose brittle edge cases in complex hardware stacks. The combination of community vigilance, vendor triage, and disciplined backup practices kept this incident from turning into a large‑scale catastrophe, but it also highlighted weak points in testing and communication that deserve attention if similar regressions are to be prevented in the future. (tomshardware.com, neowin.net)

Source: TweakTown Windows 11 SSD scare - Phison finds No Fault after 4,500 hours of testing

ChatGPT · Aug 27, 2025

The recent Windows 11 servicing wave that included security updates KB5063878 and the related preview KB5062660 ignited a flurry of alarm when hobbyist testers and everyday users reported NVMe SSDs disappearing — in some cases permanently — during large sustained writes, and much of the early traffic pointed at drives using Phison controllers. Phison’s follow-up statement saying its labs “dedicated over 4,500 cumulative testing hours” and ran more than 2,200 test cycles without reproducing the failure has shifted the story from an apparent mass “bricking” event to a complex cross‑stack compatibility incident that highlights the fragility of modern storage ecosystems and the limits of reproducing rare hardware/firmware/OS interactions. (tweaktown.com)

Background / Overview

Windows 11 cumulative update KB5063878 (released as part of the August 2025 servicing wave) and preview package KB5062660 were routine security and quality rollouts — but within days, community investigators posted repeatable test cases showing NVMe SSDs vanishing from the OS during large sequential writes, typically when the target drive was more than ~50–60% full and the transfer exceeded roughly 50 GB. Multiple independent test benches reproduced similar symptoms: drives disappearing from File Explorer and Device Manager, SMART and vendor telemetry becoming unreadable, and occasional file truncation or corruption. Some drives returned after a reboot; a minority required vendor tools or RMA to recover. (tomshardware.com, bleepingcomputer.com)
Microsoft acknowledged the reports, said it was investigating with partners, and asked affected users to submit Feedback Hub logs for triage. Phison publicly confirmed it had engaged partners and later summarized a lab campaign that — according to media briefings — totaled more than 4,500 cumulative hours across about 2,200 cycles and did not reproduce the reported failure mode. That lab report headline has been widely quoted, but it is vendor‑reported and, at the time of initial coverage, was not accompanied by a publicly auditable primary test log. Treat the numeric claim as Phison’s summary until raw logs or independent lab corroboration are published.

What users reported — the operational fingerprint

Short, repeatable test recipes that surfaced in community channels produced a consistent symptom set:

Drives would disappear mid-transfer during sustained sequential writes (game installs, large archive extraction, cloning).
Failures were most commonly observed when the drive was partially filled (often ~50–60% used) and after continuous writes approaching or exceeding ~50 GB.
Symptoms ranged from temporary disappearance (restored after a reboot) to unreadable SMART and telemetry data, and, in rare cases, permanent inaccessibility.
Early community collations over‑represented drives using Phison controllers and certain DRAM‑less or Host Memory Buffer (HMB)-dependent parts, though other controllers were implicated in isolated reports. (tomshardware.com, bleepingcomputer.com)

Those reproductions made the issue technically credible and urgent: consistency across several unrelated benches suggests a real host-to-controller interaction, not random hardware failures. However, community test benches lack the deep telemetry a controller vendor or Microsoft can capture, which is why reproducibility in vendor labs matters for root‑cause attribution.

Phison’s investigation: claims, limits, and legal noise

Phison’s public position evolved through three strands: acknowledge reports and investigate, coordinate with partners, and report lab results. The company said it had been made aware of “industry‑wide effects” tied to KB5063878 and KB5062660 and would collaborate with Microsoft and OEMs. In follow‑ups presented to the press, Phison stated it ran extensive validation and was “unable to reproduce” the reported failures; it also reported no partner/customer telemetry showing drives being affected at scale. (tweaktown.com, bleepingcomputer.com)
Two important caveats:

The headline “4,500+ testing hours / 2,200+ cycles” is a vendor‑reported aggregate that, in early coverage, lacked an attached lab log or raw artifacts to independently verify exactly what drives, firmware revisions, host platforms, and thermal conditions were included in the campaign. Treat the number as Phison’s summary until published test details or third‑party audits confirm it.
A falsified internal-looking Phison document circulated widely and falsely listed affected controllers and detailed guidance; Phison denounced the document as fake and took legal steps to prevent its spread. That misinformation complicated triage, imposed a distraction cost on the vendor, and underlines the risk of acting on leaked or unauthenticated advisories. (tomshardware.com)

Phison’s public mitigation guidance was measured: while they did not claim the reports were fabrications, they emphasized thermal best practices (heatsinks or thermal pads for extended workloads) and urged partners to stage firmware updates through vendor channels to ensure broad testing before consumer distribution. That advice is sensible operationally, but it does not by itself rule in or out a deeper cross‑stack interaction.

Why reproducibility is hard — the technical anatomy

Understanding why an OS update can expose SSD behavior requires appreciating that an NVMe SSD is an embedded system whose reliability hinges on a tight choreography of components:

Controller firmware (timing, garbage collection, error handling).
NAND flash behavior and SLC caching strategies.
On‑board DRAM vs. Host Memory Buffer (HMB) — DRAM‑less drives can be particularly sensitive to HMB timing and allocation changes.
Host NVMe driver, OS kernel I/O stack, and any changes introduced by updates.
Motherboard BIOS/UEFI, chipset drivers, and power delivery.
Thermal environment: ambient temperature, heatsink presence, airflow.

A small change — e.g., an alteration in how the OS allocates HMB pages or a subtle timing change in the IO queue path — can flip a latent race condition into a reproducible fault on a narrow subset of hardware. Add in SLC cache depletion at higher drive fill percentages and the effect of heat during sustained writes, and the combinations that must be matched to observe the fault grow rapidly. That explains why a vendor lab may run thousands of hours across many cycles and still not hit the precise corner case some community benches have captured.

Plausible engineering failure modes

Engineers watching the signal generally converge on a small set of plausible mechanisms that match the observed fingerprint:

Controller firmware hang / state lock: the controller may enter a state where it stops responding to NVMe admin or IO commands, making the drive appear absent to the OS. SMART/telemetry unreadable is consistent with this hypothesis. (tomshardware.com)
HMB timing/behavior changes: DRAM‑less controllers depend on predictable HMB allocation from the host; host updates can alter timing and allocation patterns and thereby stress firmware path assumptions.
SLC cache exhaustion & metadata pressure: sustained sequential writes eventually exhaust high‑performance caches and force the controller into more complex write and mapping pathways, which can trigger firmware edge cases under heavy metadata load.
Thermal exacerbation: extended heavy writes raise controller temperature; in marginal cooling scenarios, timing drift or thermal‑related instability can precipitate a hang. Phison’s heatsink guidance speaks to this possibility.

These mechanisms are not mutually exclusive. A sequence such as HMB timing shifts plus SLC cache depletion under high temperature is a realistic multi‑factor trigger for a latent firmware issue to surface.

Cross‑checking the public record (what’s verified, what’s not)

Verified facts (cross‑checked across outlets and vendor statements):

Microsoft shipped the August 2025 cumulative update tracked as KB5063878 and the preview KB5062660; community reports began appearing soon after. (pcworld.com, windowscentral.com)
Multiple independent community benches reproduced a reliable symptom set: drives disappearing mid‑write under sustained workloads, often when partially filled. (tomshardware.com, bleepingcomputer.com)
Phison publicly acknowledged the reports, engaged partners, ran internal validation campaigns, and reported an inability to reproduce the failures in its test matrix; the company also advised thermal mitigations. (tweaktown.com, bleepingcomputer.com)

Unproven or unverified claims that require caution:

The exact numeric composition of Phison’s “4,500+ hours / 2,200+ cycles” campaign (which drives, firmware IDs, host motherboards, BIOS versions, ambient temperatures) has not been published as an auditable packet of lab logs at the time of initial reporting; treat the headline figure as vendor summary.
A definitive attribution that pinpoints a single root cause (e.g., a particular Phison firmware bug or a Microsoft kernel regression) has not been published in a coordinated vendor whitepaper at the time of reporting. Investigations are ongoing and may yield a multi‑factor root cause.

When a vendor report and independent test benches diverge, the responsible forensic path is collecting telemetry from the field (SMART dumps, NVMe traces, kernel event logs), matching those to vendor traces, and reproducing the identical stack in a lab. That coordinated telemetry sharing is exactly what Microsoft and vendors are working toward. (bleepingcomputer.com)

Practical mitigation: what users and IT teams should do now

Given the credible but unresolved technical risk, the immediate priority is data protection and risk reduction. The steps below are pragmatic, ordered, and safe:

Back up critical data now. A current, tested backup is the only reliable defense against drive corruption or permanent loss.
If your system uses an NVMe SSD for critical operations and you have not installed KB5063878/KB5062660, consider staging the update in a pilot ring and running heavy‑write tests on representative hardware before broad rollout.
Avoid large sustained writes (>~50 GB) on drives that are more than ~50–60% full until you have confirmed stability or received vendor guidance. Splitting large transfers into smaller batches reduces risk.
Check your SSD vendor’s management tool (Corsair iCUE, SanDisk Dashboard, WD Dashboard, etc.) for firmware advisories and validated updates — apply firmware only after backing up and following vendor release notes.
Ensure proper cooling for M.2 modules: use a heatsink or thermal pad, maintain good chassis airflow, and monitor drive temperatures during sustained transfers. Phison explicitly recommended thermal mitigation for sustained workloads. (tweaktown.com)
IT admins: inventory drives, controllers, and firmware across endpoints, run representative sustained writing tests in a controlled pilot, and use WSUS/Intune/MECM to manage staged deployments and rollbacks. Preserve logs for any affected machine and file Feedback Hub reports as requested by Microsoft.

These steps trade short‑term convenience for long‑term data integrity — a rational posture when the impact of a failure can be catastrophic.

Security, transparency, and vendor coordination — the governance angle

The incident exposes two systemic weaknesses:

Test transparency: vendor summaries (hour counts, cycle counts) are useful, but without an auditable test matrix and raw artifacts, IT teams cannot independently verify that their specific SKUs and system configurations were covered in the vendor validation. Requesting or publishing a redacted test matrix (drive model, FW IDs, host rigs, BIOS, thermal profile) would materially improve trust and speed remediation.
Misinformation risk: the circulation of a falsified Phison advisory not only confused consumers and admins but diverted vendor resources into legal and PR actions. In tightly coupled ecosystems, forged documents can cause erroneous withdrawal of updates or improper mitigations. Vendors must protect authenticity and provide clear channels for verified advisories. (tomshardware.com)

On the positive side, the rapid engagement between Microsoft and major storage vendors — and the prompt public communications — show the ecosystem can move quickly when a credible signal appears. The remaining gap is in data sharing: deep telemetry exchange between vendors and Microsoft, with privacy‑preserving telemetry keys, will speed root‑cause and fix deployment.

Risk assessment: how worried should you be?

Probability (general population): low-to-moderate. Microsoft telemetry and vendor reporting did not initially show a broad spike in failures, and many users reported no effect. (bleepingcomputer.com, tweaktown.com)
Impact (if affected): high. Data loss, corrupted partitions, or drives requiring RMA are high-severity outcomes. A small probability × high impact scenario demands conservative mitigation.

In practice, the combination of plausible, reproducible community tests and vendor lab results that failed to replicate the issue means the risk is concentrated in particular hardware/firmware/platform permutations. Enterprises and cautious consumers should treat the update as one that warrants staged deployment and representative stress testing.

What to watch for next (the signals that will resolve the story)

SSD vendor advisories and model‑specific firmware updates that explicitly reference KB5063878/KB5062660 and list the fixed firmware IDs. Firmware patches are the likeliest permanent fix if controller logic is the cause.
A Microsoft Release Health post or Known Issue entry that codifies the problem and either proposes an OS mitigation or coordinates a Known Issue Rollback for affected channels. (pcworld.com)
Independent lab whitepapers or third‑party test reports that reproduce the failure across many representative SKUs under controlled, documented conditions — that will move the narrative from an anecdotal cluster to a validated systemic issue.
Publication of Phison’s full test matrix, or audited logs from partner labs, which would corroborate or clarify the “4,500+ hours / 2,200+ cycles” claim. Until that is public, treat the number as vendor summary rather than an independently verified metric.

Final analysis and practical takeaways

The KB5063878/KB5062660 episode is more than a single‑update controversy; it’s a systems‑engineering lesson about co‑engineered stacks. A small change in the OS or driver layer can expose latent firmware edge cases, particularly in DRAM‑less or HMB‑reliant SSD designs, and thermal or fill‑level conditions can act as force multipliers. Phison’s lab summary that it could not reproduce the failures is meaningful and should reassure many users, but it is not a categorical exoneration: reproducibility requires covering the precise combination of controller revision, NAND batch, firmware, host chipset, BIOS, HMB timing, fill state, and thermal profile. Until vendors publish coordinated, auditable fixes or Microsoft documents an OS‑side mitigation, conservative operational steps are the rational response: back up data, stage updates, avoid massive single-file transfers on suspect drives, and apply vendor‑validated firmware only after backups. (tweaktown.com)
This incident also underscores an organizational imperative: platform vendors and component suppliers must institutionalize deeper joint testing that includes bulk‑write, high‑fill, high‑temperature stress matrices and faster telemetry sharing. For now, the practical path for administrators and cautious consumers is straightforward and actionable: protect your data first, delay wide rollouts until verified fixes land, and favor verified vendor advisories over leaked or unauthenticated documents.
The story is still developing. Watch for firmware advisories from SSD brands and an official Microsoft Release Health bulletin; those artifacts are the clearest, most actionable indicators that a definitive remediation has been validated and arrived. (bleepingcomputer.com, tweaktown.com)

Conclusion: the Windows 11 SSD scare moved quickly from alarming social posts to coordinated vendor investigation and public lab statements. Phison’s extensive lab campaign and Microsoft’s telemetry both reduce the probability of a large‑scale failure wave, but they have not eliminated the possibility of isolated, severe failures under specific, hard‑to‑replicate conditions. The correct posture for end users and IT teams is conservative: back up, stage, test, cool, and wait for vendor‑verified firmware or Microsoft guidance before resuming heavy bulk-write workloads at scale.

Source: TweakTown Windows 11 SSD scare - Phison finds No Fault after 4,500 hours of testing

ChatGPT · Aug 28, 2025

Microsoft’s August cumulative for Windows 11 (KB5063878) lit a firestorm of community reports claiming large file copies could make some NVMe drives “vanish” or return corrupted after a reboot — but a coordinated vendor investigation led by NAND controller maker Phison found no reproducible defect after thousands of hours of lab testing, and Microsoft says it has seen no telemetry-driven increase in disk failures while it actively collects affected-user feedback. (tomshardware.com) (bleepingcomputer.com)

Background

Within days of Microsoft’s Patch Tuesday release for Windows 11 24H2 (the combined SSU + LCU tracked by the community as KB5063878), hobbyist testers and specialist outlets published a repeatable failure fingerprint: during sustained sequential writes (commonly reported near ~50 GB of continuous write traffic) to drives that were already partially filled (roughly 60% or more used), some NVMe SSDs momentarily disappeared from Windows and, in a minority of cases, did not return in a usable state without vendor-level intervention. (tomshardware.com, notebookcheck.net)
Those early community reproductions focused attention on drives using Phison controllers because several affected models in public test lists used Phison silicon. That prompted a joint investigative response: Microsoft asked for detailed customer feedback, and Phison began extended internal validation across multiple drive samples and firmware versions. (bleepingcomputer.com, neowin.net)

What the vendors said — the core facts

Microsoft: the company told investigators it was aware of reports and was working with storage partners to reproduce and diagnose, but stated it had not yet seen a platform-wide telemetry signal indicating increased disk failures. Microsoft invited affected users to submit Feedback Hub reports and work with support to collect additional diagnostic details. (bleepingcomputer.com)
Phison: after dedicating extensive lab effort — the company described more than 4,500 cumulative testing hours and over 2,200 test cycles across the drives reported as potentially affected — Phison said it could not reproduce the disappearance/corruption behavior in its validation environment and recommended that users follow standard best practices (including thermal management/heatsinks for extended workloads). (tomshardware.com, neowin.net)

Those vendor statements shifted the narrative from “the update is killing SSDs” toward a more complex hypothesis: an interaction between specific workload patterns, drive firmware, system configuration, and environmental conditions rather than a single, easily reproducible OS bug that universally bricks drives. (tomshardware.com, neowin.net)

How the problem was first reported (technical fingerprint)

Independent testers and community contributors described a consistent chain of events:

Start a continuous large copy operation (examples posted publicly use game patches or a single large file) of roughly 50 GB or more.
The target drive is already moderately full (commonly cited ≈ 60%+ utilization).
During sustained writes, the drive stops responding to Windows I/O, disappears from Explorer/Device Manager, and SMART/controller telemetry may become unreadable.
In many cases, a reboot restores drive visibility; in others, partitions or files written during the incident are corrupted or inaccessible. (tomshardware.com, notebookcheck.net)

That repeatable fingerprint is what elevated the issue beyond anecdote and made it a triage priority for vendors and enterprise IT teams. (tomshardware.com)

What Phison’s lab work means — and what it does not

Phison’s public test summary is significant: if a well-resourced controller vendor cannot reproduce a field failure using hundreds or thousands of hours of structured test cycles, that strongly suggests the root cause is more conditional than a deterministic OS regression that always produces the same failure on the same hardware.
At the same time, “unable to reproduce” is not the same as “no user was harmed.” Field failures that depend on a complex confluence of firmware version, drive wear level, host BIOS/UEFI settings, third-party drivers, thermal state, or even counterfeit/falsified firmware can be invisible in an OEM lab unless the vendor exactly matches the real-world conditions. Multiple independent outlets noted that community reproductions pointed to a real, narrowly distributed regression that warranted caution while vendors continued triage. (neowin.net, bleepingcomputer.com)

Why “unable to reproduce” happens

Lab test matrices may not include the exact combination of user firmware, aging NAND characteristics, or OEM-supplied firmware binaries that appear in consumer systems. (neowin.net)
Some failures only show under particular ambient temperatures or when a drive’s spare-block pool and wear leveling have reached certain states after extended use. Phison explicitly recommended thermal mitigation (heatsinks/pads) for extended workloads. (tomshardware.com)
A forged/adversarial advisory circulated in some channels and complicated public triage, prompting Phison to call out falsified documentation and focus attention on verified test results instead.

How likely is this to affect you?

At present the evidence points to a low but non-zero risk profile for a subset of workloads and hardware combinations:

The phenomenon has been reproduced consistently in multiple community labs under the specific sustained-write scenario, which means the failure class is real for some configurations. (tomshardware.com, notebookcheck.net)
Vendor telemetry and wide-scale telemetry from Microsoft did not, at the time of their statements, show a broad uptick in disk failures attributable to the update. That suggests the issue is not widespread across the millions of Windows installations that received KB5063878. (bleepingcomputer.com)

Put simply: if you’re a heavy-writes user (video editors, content creators, transferring large game installs, backup appliances) on a specific SSD model listed in community collations — especially older drives or DRAM‑less models that rely on Host Memory Buffer (HMB) — it’s prudent to exercise caution. For ordinary desktop use, the probability of encountering the exact triggering pattern is lower. (tomshardware.com, notebookcheck.net)

Technical hypotheses under discussion

Multiple plausible mechanisms have been proposed by engineers and independent testers; none have been singularly confirmed by public vendor forensics at the time of the vendor statements:

Host Memory Buffer (HMB) interaction: changes in how the OS allocates host RAM to DRAM-less SSDs can expose firmware edge cases. Earlier 24H2 discussions involving WD drives and HMB allocation demonstrate how small host-side adjustments can surface latent controller bugs.
Sustained write path / cache exhaustion or leak: sustained sequential writes can stress write caching, FTL (flash translation layer) operations, or TRIM processing — especially on partially full devices — and may lead to controller timeouts or reset conditions that the host interprets as “drive removed.” Community test patterns consistently point to large sequential writes as the trigger. (tomshardware.com)
Thermal conditions: SSD temperature during extended writes can cause throttling or unpredictable controller behavior on drives without robust cooling; Phison’s guidance to use heatsinks for heavy workloads is consistent with this hypothesis. (tomshardware.com)
A combination of firmware + host driver changes: OS updates that alter NVMe driver behavior, storport handling, or HMB allocation can reveal a firmware robustness gap only visible under particular host/firmware pairings. (tomshardware.com, bleepingcomputer.com)

All of these remain plausible; comprehensive forensic confirmations require correlated logs from the host, controller crash dumps, and vendor-provided firmware traces. That level of cross-stack forensic correlation takes time and cooperation. (bleepingcomputer.com, neowin.net)

Practical guidance for Windows users and admins

Until vendors publish firmware or Microsoft issues an OS-level mitigation, take conservative, risk‑minimizing steps:

Back up critical data now. Always prioritize verified backups before applying or testing major updates. This is non‑negotiable.
Avoid sustained large sequential writes (50 GB+ continuous copies) on systems that have received KB5063878 or the related preview KBs until your drive vendor confirms your model and firmware are validated. (tomshardware.com)
Check and update SSD firmware using the manufacturer’s official tools (Western Digital Dashboard, Samsung Magician, Crucial Storage Executive, Corsair SSD Toolbox, or vendor firmware pages). Firmware fixes are the most common reliable remediation for controller-interaction issues.
If using high-performance M.2 drives for extended workloads, install an NVMe heatsink or ensure adequate chassis airflow to reduce thermal excursions. Phison specifically recommended thermal measures for extended workloads. (tomshardware.com)
For enterprise deployments: stage the KB5063878 rollout using WSUS/patch management, inventory NVMe models and known vulnerable SKUs, and hold updates for machines with drives matching community hit lists until vendor verification.

How to gather useful diagnostics if you experience the issue

Stop writes immediately when a drive disappears. Do not reformat unless you’ve imaged the device.
Capture Windows Event Viewer logs (System and Application) and Windows Reliability Monitor entries.
Use vendor utilities (e.g., CrystalDiskInfo, vendor tools) to capture SMART data and controller firmware versions.
If possible, create a sector-level image (dd, vendor imaging tools) before attempting repairs when data is valuable.
Report the problem via Microsoft Feedback Hub and your SSD vendor’s support channel, attaching logs and reproducible steps. Microsoft and vendors have been soliciting such artifacts for cross-stack correlation. (bleepingcomputer.com, neowin.net)

What to watch for from vendors and Microsoft

Firmware advisories and targeted firmware updates for affected controller SKUs. Vendors typically publish firmware release notes and update utilities that identify whether a drive is in-scope.
Microsoft release notes or out‑of‑band mitigations that alter HMB allocation or storport behavior if a host-side change is implicated. Microsoft’s request for more affected-user reports underscores that the company is still collecting data to decide on any OS patches. (bleepingcomputer.com)
Verified forensic write-ups from independent labs and reputable specialist outlets explaining precise reproduction steps, telemetry captures, and root-cause analysis; those will be the most reliable indicators a cross-stack fix has been validated. (tomshardware.com, notebookcheck.net)

Risks beyond bricking: misinformation and operational cost

The story also highlights two secondary risks every IT professional and enthusiast should consider:

Misinformation and forged advisories. A falsified internal advisory circulated in some channels and wrongly pinned blame to specific controllers. That amplified fear, complicated triage, and could cause unnecessary RMAs or premature recall actions. Vendors warned that not all circulating advisories were authentic, and false documents may have been deliberately distributed. Treat unauthenticated memos with skepticism and verify vendor channels.
Operational cost of caution. Organizations that aggressively block or rollback updates to avoid a low-probability regression will pay a security/patching cost. Conversely, blind immediate deployment risks edge-case failures. The right approach is measured staging: inventory, risk-assess, and deploy with vendor-validated mitigation plans.

Bottom line — a balanced read

The available evidence paints a nuanced picture:

Community test benches reproduced a narrow, repeatable failure fingerprint during heavy sequential writes that made some NVMe drives disappear or return corrupted state after installing KB5063878. (tomshardware.com, notebookcheck.net)
Microsoft has acknowledged the reports and asked for detailed telemetry and feedback, while stating it has not yet seen a platform-wide telemetry signal of increased disk failures. (bleepingcomputer.com)
Phison’s lab testing — thousands of cumulative hours and thousands of cycles — reported an inability to reproduce the failure in their validation matrix, and Phison recommended thermal mitigation for sustained workloads while continuing to monitor. (tomshardware.com, neowin.net)

That combination suggests the incident is real but rare, and that the most responsible user action today is prevention: back up, avoid high‑risk sustained writes on patched systems, keep SSD firmware current, and follow official vendor guidance. For administrators, stage updates and short‑circuit deployment on systems running critical workloads until vendor/OS mitigations are confirmed.

Final recommendations (clear checklist)

Back up essential data and ensure off‑device or cloud backups are recent.
Delay mass deployment of KB5063878 on systems with NVMe drives until vendor validation.
Avoid single-session, sustained sequential writes (50 GB+) on upgraded systems.
Update SSD firmware from the manufacturer’s official utility and note firmware build numbers.
Install heatsinks or improve airflow for M.2 drives used for extended write workloads.
If you experience a disappearance or corruption event: preserve logs, image the drive if data is valuable, and open coordinated support tickets with both Microsoft and the SSD vendor. (tomshardware.com, bleepingcomputer.com)

The episode is an important reminder of a basic truth in modern systems engineering: storage reliability is a cross‑stack problem. Operating system changes, controller firmware, Vendor-supplied firmware, thermal environment, and workload patterns all interact. Until vendors publish a clear, validated fix (either firmware updates or an OS mitigation), prudent staging and solid backups are the most effective defenses.
Conclusion: the headline “Windows 11 update is killing SSDs” is an overreach; the more accurate characterization is that KB5063878 has exposed a narrow, conditional failure mode in some environments. Phison’s inability to reproduce the failure in controlled lab testing is reassuring, but it does not retrospectively erase reports from hobbyists who documented real data disruptions. Treat the risk seriously, act conservatively, and follow manufacturer guidance while vendors and Microsoft finish the cross‑stack forensic work. (neowin.net, bleepingcomputer.com)

Source: Android Headlines No, Windows 11’s Latest Update Isn’t Killing Your SSDs

ChatGPT · Aug 28, 2025

Phison’s lab campaign—more than 4,500 cumulative test hours and some 2,200 cycles—says it could not reproduce the Windows 11 KB5063878 “vanishing SSD” reports, but the episode still exposes a brittle cross‑stack interaction that administrators, gamers, and system builders should treat as a live risk until a joint, auditable post‑mortem is published. (tomshardware.com) (neowin.net)

Background / Overview

In mid‑August 2025 Microsoft shipped its Windows 11 24H2 cumulative update (commonly tracked by the community as KB5063878, with a related preview package KB5062660) as part of the normal Patch Tuesday servicing wave. Within days, hobbyist testers and independent labs reported a repeatable failure pattern: during sustained large writes—commonly cited as a continuous transfer of roughly 50 GB or more—some NVMe SSDs would become unresponsive, disappear from Windows’ Device Manager and File Explorer, and in a minority of cases return corrupted or remain inaccessible after reboot. Multiple outlets and community threads converged on a similar operational fingerprint, which is why the reports were quickly elevated to vendor triage. (windowscentral.com) (tomshardware.com)
The early public signal frequently pointed to drives using Phison NAND controllers, particularly consumer DRAM‑less modules that rely on Host Memory Buffer (HMB) behavior. That concentration prompted Phison to publicly investigate the claims with Microsoft and OEM partners. Microsoft, for its part, acknowledged it was “aware of these reports” and asked affected customers to submit Feedback Hub logs while it coordinated deeper telemetry collection and partner triage. (bleepingcomputer.com, windowscentral.com)

What the community tests actually reported

Independent reproductions were specific and, crucially, repeatable in a number of test benches—conditions that moved the story from rumor to triage.

Typical trigger: a sustained sequential write of tens of gigabytes (often ~50–62 GB in published recipes) to a target SSD that was already partially full—commonly ~50–60% capacity. (windowscentral.com, tomshardware.com)
Symptoms: the NVMe device becomes unresponsive mid‑write, disappears from the operating system and BIOS in the worst cases, SMART and vendor telemetry are unreadable, and files in flight can be truncated or corrupted. In many cases a reboot restored visibility; in a smaller subset of cases the drive required vendor tools or RMA. (tomshardware.com, pcworld.com)

One well‑publicized test campaign examined 21 SSDs and found about half experienced some form of the failure symptom under the specific workload used by the tester; one SATA unit reportedly became unrecoverable. These community test logs were the spark that forced vendor attention. That empirical footprint—repeatable steps that produced the same symptom across benches—gave engineers a concrete forensic recipe and made a coordinated vendor response necessary. (tomshardware.com, windowscentral.com)

Phison’s investigation and the 4,500‑hour claim

Phison responded to the reports by running an internal validation campaign. The company summarized its efforts with two headline claims: it “dedicated over 4,500 cumulative testing hours” and ran “more than 2,200 test cycles” across the drives reported as potentially impacted, and it was unable to reproduce the reported issue in its lab. Phison also said no partners or customers had reported drives failing at scale in their telemetry during the test window. (neowin.net, hothardware.com)
Phison’s follow‑up message recommended common‑sense thermal best practices—use of heatsinks or thermal pads for drives subjected to extended, heavy write workloads—while it continued telemetry monitoring and partner coordination. That recommendation is sensible operational advice but does not, on its own, settle the root‑cause question. (neowin.net, tech.yahoo.com)
Caveat: the numeric claim of “4,500 hours” appears in vendor statements and media summaries; at the time of reporting those figures were not accompanied by a publicly auditable raw log or test artifact. Treat the numeric summary as Phison’s reported figure pending publication of a full lab report.

The plausible technical mechanisms (what engineers are examining)

Storage failures that appear only under specific, heavy write patterns nearly always point to cross‑stack timing, buffer, or state management issues—not to sudden physical NAND destruction. Several plausible mechanisms emerge from the public narrative and past precedent:

1) SLC cache and write‑path exhaustion

Modern consumer SSDs use dynamic SLC caches and prioritized write paths to deliver high burst performance. Sustained sequential writes—especially when the drive is partially full—can exhaust or force fallback behaviors in firmware, triggering complex metadata updates or garbage‑collection cycles that, if mishandled, can cause firmware to hang or misreport state. This is consistent with the symptom set (drive disappears; SMART unreadable). (tomshardware.com)

2) Host Memory Buffer (HMB) timing on DRAM‑less parts

DRAM‑less SSDs rely on the host to provide memory windows (HMB). Changes in how the OS or NVMe driver allocates or sequences HMB usage can expose latent races or timing bugs in controller firmware. Windows update churn that affects kernel I/O behavior or buffer allocation could plausibly alter HMB timing and expose an edge case. Earlier Windows 11 interactions have shown HMB sensitive designs to be more brittle under some OS changes. (windowscentral.com, tomshardware.com)

3) Thermal stress and throttling

Sustained heavy writes generate heat. If thermal throttling or prolonged high die temperatures intersect with aggressive internal housekeeping (GC, wear‑leveling), firmware paths could misbehave. Phison’s advice to use heatsinks implies the company considers thermal state a plausible aggravator, even if it did not observe deterministic failures in its lab matrix. (neowin.net)

4) Rare firmware / NAND permutations and ageing effects

A drive’s failure behavior can depend on NAND die revision, channel allocation, firmware patch, and even an overprovisioning/spare‑block pool shaped by the drive’s prior usage and wear. Lab tests that use fresh samples and a limited range of firmware builds can miss a field failure that requires an unlucky combination of ageing, a specific firmware revision, and a distinct host stack state. That explains why some community benches reproduced the issue while vendor tests did not.

Reproducibility, telemetry, and why vendors disagree with users

The episode highlights a recurring investigative friction: vendor telemetry and lab matrices versus anecdotal, reproducible community benches.

Vendor telemetry covers millions of devices and can rapidly detect large statistical anomalies—Phison and Microsoft reported no telemetry surge consistent with mass bricking at the time of their statements. (bleepingcomputer.com, hothardware.com)
Community labs delivered small‑scale yet repeatable reproductions under very specific conditions that may not be captured by broad telemetry. Small sample sizes can still be real and dangerous when they lead to unrecoverable data loss for affected users. (tomshardware.com, windowscentral.com)

“Unable to reproduce” is not synonymous with “proven safe.” It means Phison’s particular test matrix and telemetry search did not reveal a deterministically reproducible, widespread bug. The real world contains messy combinations of firmware, NAND, host BIOS, and usage history that a tightly scoped lab campaign can miss. Independent reproductions that follow a clear recipe are valid forensic leads; vendor inability to reproduce is an important counter‑signal but not a final exoneration.

Risk assessment — who is truly at risk?

The evidence so far points to a low but non‑zero risk for certain heavy‑write workloads on specific hardware/firmware permutations.

Users most at risk: those performing large contiguous writes (game installs, archive extraction, cloning, video exports) to SSDs that are >50–60% full. The community reproductions hinge on that approximate fill level and file size threshold. (windowscentral.com, tomshardware.com)
Hardware patterns: early reports concentrated on drives using Phison controllers, especially DRAM‑less designs that rely on HMB, but later lists showed other controllers and models implicated in isolated cases—meaning the vector is likely an interaction rather than a single vendor’s firmware failing universally. (tomshardware.com, therootuser.com)
Scale: vendor telemetry did not show a large‑scale RMA or failure spike at the time of reporting; this suggests the issue is not widespread across the millions of systems that received KB5063878, but it can be severe for those who encounter it. (hothardware.com, bleepingcomputer.com)

The risks of premature narratives and unverifiable claims

In parallel with community tests and vendor statements, falsified documents and sensational claims circulated on social platforms, complicating triage and attracting conspiratorial angles. Some outlets and threads speculated about deliberate hoaxes or targeted misinformation; those claims remain unverified. Vendors including Phison explicitly disavowed forged advisories and urged partners and users to rely on formal communications. Treat any leaked lists or unauthenticated advisories with extreme caution; they can mislead remediation efforts and inflame panic. (tech.yahoo.com, neowin.net)

Practical guidance — what individuals and IT teams should do now

Conservative, risk‑managed actions will protect data and give vendors time to produce a verified fix or advisory.

Prioritize backups.
Ensure current system images and user data backups exist before applying high‑risk updates or performing heavy write operations. If you use incremental or snapshot backups, verify restore capability. This is the single best defense against data loss.
Stage updates in pilot rings.
Don’t deploy KB5063878 and related updates broadly into production or gaming fleets without representative heavy‑write tests. Use WSUS, Intune, or your patching tool to defer rollout for storage‑sensitive machines.
Run targeted stress tests on representative hardware.
If you manage fleets, run sustained sequential write stress tests (50+ GB) on representative SKUs and firmware revisions before approving the update. Maintain a matrix of drive model, firmware, and observed behavior.
Avoid single, very large writes on suspect drives.
Temporarily split large game installs or archive operations into smaller batches and keep free space above the community‑observed threshold where possible (e.g., >40% free).
Monitor vendor advisories and RMA channels.
Watch SSD manufacturer support pages for firmware notices and apply validated firmware via official utilities where available.
Consider thermal mitigation.
For M.2 NVMe modules used in sustained workloads, ensure adequate cooling—heatsinks or chassis airflow—as advised by Phison. Thermal care does not replace firmware fixes, but it reduces a plausible aggravating factor. (neowin.net)
If you experience the issue, collect forensic evidence.
Gather event logs, NSR and NVMe traces, Feedback Hub logs, and vendor utility dumps before rebooting if possible; submit them to Microsoft and the SSD vendor to aid correlation.

What to watch for from Microsoft and vendors

Resolution requires coordinated telemetry correlation and a public, auditable post‑mortem:

A Microsoft advisory that lists reproductions, telemetry findings, and a mitigation roadmap (hotfix, driver change, or rollback guidance). Microsoft has asked for customer reports and is working with partners at the time of writing; formal remediation guidance is the key next public signal. (bleepingcomputer.com)
Firmware advisories and validated firmware images from SSD vendors that explicitly reference affected controller families and the windows update interaction. Phison’s lab report (with raw test artifacts) or vendor test logs from SSD makers would materially reduce uncertainty. (neowin.net)
Independent lab validations that reproduce vendor fixes and publish reproducible test artifacts—those are critical for establishing confidence that a change actually resolves the cross‑stack fault.

Final analysis — why this story matters beyond a single KB

This incident is a textbook example of modern platform fragility: large OS updates touch deep, timing‑sensitive kernel subsystems whose behavior is co‑engineered with peripheral firmware. When a failure requires a precise confluence of workload, firmware revision, device wear, and host driver behavior, it becomes extremely hard to prove or disprove at scale without coordinated telemetry and shared forensic artifacts.
Phison’s statement that its lab work could not reproduce widespread failures after thousands of hours is an important counterpoint to alarm—but it is not an unconditional exoneration. The community reproducibility of a narrow failure fingerprint remains a meaningful signal that must be followed to a firm, auditable conclusion. Until vendors publish a joint technical post‑mortem or validated firmware, the safest posture for those with storage‑sensitive workloads is cautious staging, robust backups, and avoidance of large continuous writes on drives near capacity. (tomshardware.com, hothardware.com)

Conclusion

The immediate headline—“Windows 11 update is bricking SSDs”—has been substantially softened by Phison’s extended lab campaign and by Microsoft’s early telemetry checks, but the incident still exposes systemic weaknesses in how OS vendors and hardware makers validate updates against real‑world, heavy‑write workloads. Phison’s inability to reproduce the failure in its test matrix (after a reported 4,500+ hours of testing) is reassuring for many users, yet independent reproductions and several credible user reports mean the risk of isolated but severe data loss remains.
Actionable takeaways are straightforward and durable: back up, stage updates in pilot rings that include heavy‑write scenarios, avoid large single‑pass writes to near‑full SSDs, and follow official vendor advisories for firmware and hotfixes. A formal, joint vendor‑Microsoft post‑mortem with published test artifacts would move this episode from “unsettling” to resolved. Until that document exists, treat the update and the implicated workload as a live, manageable risk rather than a closed case. (bleepingcomputer.com, neowin.net)

Source: PC Gamer After 4,500 hours of testing, SSD controller specialist Phison rules out allegations that a Windows 11 update is bricking drives

ChatGPT · Aug 28, 2025

Phison’s terse lab update — that its engineers “could not reproduce” the NVMe disappearances reported after a recent Windows 11 cumulative update — has shifted an alarmed headlines cycle into a cautious, technical debate about reproducibility, telemetry, and how the modern storage stack fails under extreme conditions. rview
Windows 11’s mid‑August cumulative servicing (commonly tracked in community reporting as KB5063878, with a related preview KB5062660) triggered multiple independent reports from hobbyist testers and specialist outlets: during sustained, large sequential writes some NVMe SSDs would become unresponsive, disappear from File Explorer and Device Manager, and in some instances return corrupted or inaccessible. The community reproductions converged on a repeatable fingerprint — sustained sequential writes on the order of tens of gigabytes (commonly around ~50 GB) to drives that were already partially full (roughly 50–60% used) — that made the issue technically credible and urgent.
Phison, the NAND-ceny consumer and OEM NVMe modules, acknowledged the investigation and then published a short validation summary. In that summary Phison reported it had dedicated thousands of lab hours to reproduce the issue — figures widely summarized as more than 4,500 cumulative testing hours and ~2,200 test cycles — and stated it was unable to reproduce the reported disappearance/corruption behavior in its validation environment. Microsoft, meanwhile, said it was aware of customer reports but had not observed a platform‑wide telemetry signal indicating a spike in disk failures.
Those two positions — repeated community reproductions on oneethat cannot reproduce the symptom on the other — define the core tension in this episode. That tension is not merely semantic: it affects how administrators, system builders, and consumers choose to respond to updates that may intersect with fragile hardware or firmware edge cases.

What the community reports actually describe

A concise technical fingerprint

Independent testers and multiple specialist outlets published step‑by‑step reproductions that commonly shared these elements:

The write workload is sustained and sequential, often an uninterrupted transfer or extraction of tens of gigabytes (test recipes frequently cited ~50 GB).
The target NVMe drive is already moderately or heavily used (community threads often mention drives ay).
Symptoms range from a temporary disappearance from the OS (restored by reboot) to a more severe loss where SMART and vendoradable and partitions or files are corrupted or inaccessible.

This repeatable recipe is precisely why the issue gained traction rapidly: reproducibility in independent benches makes the problem more than anecdoy reproductions across different testbeds and drives reinforced the signal and forced vendor attention.

Which drives and controllers were flagged?

Early high‑visibility lists included several drives built around Phison controller families (community collations repeatentroller lines and DRAM‑less/HMB‑reliant modules among the frequently observed examples). That over‑representation prompted Phison’s focused lab campaign, but community lists also contained non‑Phison examples, underlining that the phenomenon may depend on firmware revision, factory configuration, or host stack behavior rather than strictly on controller vendor.

Phison’s response and lab program

Phison’s follow‑up message shifted the narrative: the vendor stated it had invested substantial lab effort and, after the described testing campaige* the failure patterns reported by community testers. The company also explicitly recommended thermal mitigation — heatsinks or improved cooling — for high‑performance M.2 modules as a prudent precaution during sustained workloads.
Two common, consequential claims from the vendor updates and subsequent reporting:

The numeric testing summary (reported broadly as 4,500+ cumulative hours and ~2,200 test cycles) is used as a confiden thoroughly investigated the issue.
Phison’s inability to reproduce the failure in tightly controlled lab conditions is widely cited as evidence the update is not broadly bricking drives at a population scale.

Both claims are meaningful but require careful interur/cycle numbers are vendor‑summarized and were not accompanied, in public reporting at the time of the statements, by audited lab logs or a primary, publishable test artifact that ies to validate the lab matrix. Several community analysts have cautioned that the absence of an auditable, published test log limits how definitive the numeric claim can be treated.

Why a vendor lab may fail to reproduce a field failure

The difference between a community bench that reproduces a failure and a vendor lab that does not is familiar territory in hardware forensics. Several plausible, documented reasons explain why this happens:

Fiity: many branded drives use vendor‑specific firmware images and factory settings. Reproducing the exact consumer unit — including its labeled firmware, NAND types, and board revision — is nontrivial. Community reproductions sometimes involve specific branded SKUs whose vendor firmware differs from Phison’s reference images.
Device wear and spare‑pool state: the NAND spare block pool and wear‑leveling metadata evolve as a drive ages. Failures that depend on a particular state of the spare pool or garbage‑collection cadence can be invisible on brand‑new test units.
Host software and driver stack: operating‑sysr tweaks, third‑party drivers, BIOS/UEFI settings, or even Windows update path differences can create host timing that triggers a latent controller bug. These cross‑stack interactions are notoriously hard to mirror in a single lab unless the lab incme platform stack and cumulative configuration as the field reports.
Thermal and mechanical conditions: sustained sequential writes generate high temperatures; thermal throttling or heat‑related state changes can alter controller behavior in ways not obvious in ambient lab conditions. Phison explicitly recommended heatsinks as a precautionary mitigation.

In short: “unable to reproduce” does not prove “t does make a widespread, deterministic OS regression less likely, but it also leaves open a conditional or state‑dependent failure mode that requires deeper joint forensics.

The forged advisory and communication noise

Complicating the incident was the circulation of a forged internely attributed a definitive, exclusive fault to Phison silicon. Phison publicly denounced the document as falsified and signaled legal action, underscoring how quickly unauthenticated documents can amplify panic and misdirect forensic work. The presence of forged materials in public channels increases the noise floor and makes triage slower and more error‑prone.

Critical analysis — strengths and limitations of the parties’ positions

Strengths in the vendor and Microsoft responses

Phison’s lab engagement and public acknowledgement turned what might have been a slow, closed‑door process into a visible, coordinated investigation. The sheer scale of reported testing hours and cycles, if accurate, reflects a meaningful allocatiorces and reduces the likelihood of a trivial, easily reproducible defect.
Microsoft’s telemetry check — the company reported no platform‑wide signal of increased disk failures associated with the update — is significant: a genuinely ubiquitous regression across millions of endpoints would likely register in global telemetry.

Limitations and unresolved risks

Lack of auditable lab logs: the numeric testing claims (hours/cycles) are useful but, without published lab test matrix, they remain vendor summaries. That absence matters to independent verification: the community’s confidence would be higher if Phison or Microsoft published structured reproduction attempts and machine‑readable traces.
Real‑world conditiona reproductions remain compelling because they are repeatable in multiple independent benches under a specific workload pattern. That suggests a narrow, conditional failure mode that can be severe for affected units and use cases (e.g., large game installs, media exports) even if it’s not statistically widespread.
The dataset of affected units is heterogeneous: many branded drives, multiple contrvarying platform stacks were represented in early lists. That heterogeneity complicates single‑vendor attribution and underlines the need for cross‑stakeholder telemetry correlation.

Practical impact: who is most at risk?

The immediate risk profile is low but non‑zero and use‑case dependent. The scenarios with elevated risk include:

Heavy‑writeeators, gamers installing large titles, and any workload that performs tens of gigabytes in a single continuous operation.
Drives near capacity: modules that are already 50–60% full (the community trigger window) appear more likely to reproduce the disappearance behavior.
Systems want modules or particular branded firmware revisions that were over‑represented in early community lists.

For most casual users with routine workloads, the immediate probability of encountering the failure is low given vendor and Microsoft telemetry statements; however, the consequences for an affected user can be severenaccessible partitions), which is why conservative mitigation is warranted.

Recommended actions — short term and operational

The appropriate defes risk tolerance against operational realities. Practical, prioritized steps for users and administrators:

Back up first. Ensure current, or any drive performing critical work. This is the single most important risk‑mitigation step.
Stage updates. For organizations, hold KB5063878 (or related cumulative servicing packages) in pilot rings that include machines performing heavy write workloads and representative SSD SKUs. Use WSUS, Intune, or equivalent to control deployment.
Avoid sustained single‑pass large writes on recently updated systems while vendors continue triage — split large transfers into smaller chunks where feasible. Community tests indicate splitting large writes often avoids the failure in some benches.
Monitor vendor support pages and SSD utilities. Apply only validate drive makers and follow their utilities for safe updates. Do not apply unofficial or leaked firmware.
Collect forensic evidence if affected. If a disappearance occurs, collect event logs, NVMe traces, vendor utility dumps, and Feedback Hub logs ssible, and submit them to Microsoft and the SSD vendor. Those artifacts materially aid root cause correlation.
Use thermal mitigation where appropriate. For sustained high‑IO workloads, ensure adequate M.2 cooling and chassis airflow; Phison recommrecautionary measure.

These steps are pragmatic and low‑cost compared with the potential downside of data loss.

Longer term: systemic fixes and industry lessons

This incident highlights g and process priorities for the Windows ecosystem:

Better cross‑vendor telemetry sharing: structured, high‑fidelity telemetry exchange between OS vendors, controller vendors, and OEMs would shorten forensic cycles and reduce uncertainty. Correlating NVMe controller traces with h and update diffs would allow faster, auditable attributions.
Expanded representative test matrices for updates: as hardware diversity grows (DRAM‑less modules, HMB reliance, many brations), update test matrices must include heavy‑write workloads and representative consumer SKUs to catch timing‑sensitive regressions before wide rollout. This is operationally costly but reduces the chance of narrow but severe regressions escaping QA.

Vendors and platform maintainers must weigh the cost of larger, more representative test suites against the reputational and support costs of field incidents that can damage user trust.

Where the public record remains incomplete

Key open questions that would materially reduce uncertainty if answerishable, auditable Phison test log or a joint Microsoft‑Phison forensic report that lists the exact test matrix, hardware SKUs, firmware versions, and raw traces from both successful and unsuccessful reproduction attempts. Several community analysts flagged that the numeric testing claims lacked accompanying primary artifacts in public reporting.

Correlated telemetry slices from Microsoft thatompany searched for and ruled out a platform‑wide increase in disk failures — the methodology and sampling would help interpret the “no telemetry increase” claim.

Absent those artifacts, the technical debate will persist: vendor labs offer strong counterevidence to a mass bricking claim, while community benches offer equally strong evidence that a narrow, real fault class exists under specific conditions.

Final assessment and guidance

Phison’s inability to reproduce the reported SSD disappearances after thousands of lab hours is meaningful and lowers the probability that the Windows 11 cumulative update is deterministically bricking a large swath of drives. At le independent community reproductions and credible user reports — under a narrowly defined workload profile — mean the risk of isolated, severe data incidents remains real for some configurations.
Practically:

Treat this as a *managfor heavy‑write workloads and for drives near capacity.
Prioritize backups, staged update rollouts, representative testing for fleets, and the application of vendor‑validated firmware where available.
Demand auditable forensic artifacts if you are an enterprise stakeholder: publishable test logs and correlated telemetry shorten remediation timelines and restore confidence.

The incident is a useful reminder that the modern storage stack is a co‑engineered system: operating system updates, kernel timing, NVMe driver behavior, controller firmware, and even device aging interplay in subtle ways. The responsible path forward combines conservative operational practice now with systemic improvements — better telemetry, broader representative testing, and faster vendor collaboration — that reduce the chance this kind of edge case becomes

This account synthesizes the available public reporting and vendor statements and aims to provide clear, actionable guidance for Windows users le accurately representing the limits of the current public record.

Source: Research Snipers Phison Finds No Evidence of SSD Failures After Windows 11 Update – Research Snipers
Source: OC3D Phison shrugs off Windows 11 SSD failure reports - OC3D

ChatGPT · Aug 28, 2025

Windows 11’s August servicing wave briefly looked like a potential storage disaster: users and hobbyist labs reported NVMe SSDs vanishing during large, sustained writes after installing the 24H2 cumulative update tracked as KB5063878 (and the related preview KB5062660), but Phison — the largest single-name target in the discussion — says its extended lab campaign could not reproduce a bricking behavior and found no evidence the update universally “bricks” SSDs. est surfaced within days of Microsoft’s mid‑August cumulative update for Windows 11 (commonly tracked as KB5063878, OS Build 26100.4946), when independent testers published a repeatable failure fingerprint: during sustained sequential writes (often in the neighborhood of ~50 GB of continuous data) to drives that were already partially full (commonly cited around 50–60% utilized), target NVMe drives would disappear from Windows and, in a minority of cases, return corrupted or remain inaccessible.
Those community reproductions focused atnrs because a disproportionate number of early high‑visibility reports involved Phison‑based modules. Microsoft opened an investigation and began soliciting telemetry and Feedback Hub reports from affected customers, and Phison launched an internal validation program.
What made the incident newsworthy was not merely the symptom but the apparent repea e workload profile and similar system conditions produced the “disappearance mid‑copy” scenario in multiple independent labs, which made the reports technically credible and elevated vendor response urgency.

What Phison reported — and why the community pushed back

Phison published a terse validation summary stating it had “dumulative testing hours across the drives reported as potentially impacted and conducted over 2,200 test cycles,” and that it could not reproduce the disappearance or permanent corruption behavior in those tests. The company also said no partners or customers had reported the issue at scale at the time of its testing.
That statement prompted a mixed reaction. Some community members welcomed the reassurance; others reacted with skepticism because several users andcon systems matching the published repro recipes. A third group pointed out that Phison’s lab results — while meaningful — did not end the question: unable to reproduce is not the same as proven safe.
Phison’s engineers reportedly tried to mirror public reproductions closely — down to the same workload cadence and even the same game file versions used in a test scenario — and still did nothe company recommended practical mitigations such as improved thermal management during extended writes (heatsinks for M.2 modules) as a precaution.
Important caveat: the numeric claim about “4,500 hours” comes from Phison’s reporting but the underlying primary lab logs and raw test artifacts were not published publicly at the time, so that figure remains *re rather than independently auditable in the public domain. Treat that numeric detail as provisional until Phison or an independent lab releases test logs.

The technical fingerprint: what testers actually reproduced

Independent labs and community testers that reproduced the failure converged on a consistent set of conditions:

Target workload: long, continuous sequential writns of gigabytes — commonly reported around ~50 GB of continuous data written.
Drive state: SSDs already moderately to heavily used — often ≈ 50–60% full — which is significant because internal caching behavior and garbage collection dynamics change as free pool shrinks.
Symptom: the SSD becomes unresponsive to Windows File Explorer, Device Manager and vendor utilities, and in some cases returns with unreadable SMART/controller telemetry or corrupted files written during the incident. Reboot recovered the device in maty the drive required vendor tools or an RMA.

This repeatable fingerprint is what led storage‑focused outlets and hobbyist testers to believe the issue was a host‑to‑controller interaction — a timing or command sequence change in the Windows I/O stack that could push specific controller firmware into an unrecoverable state under particular

Why reproducibility is hard — and why Phison’s lab result matters, but not definitively

Modern NVMe SSDs are embedded systems composed of NAND flash, a controller SoC, controller firmware (FTL), optional DRAM or Host Memory Buffer (HMB), the PCIe link, and the OS NVMe driver stack. Small changes in host tims or I/O scheduling introduced by an OS update can expose latent firmware bugs only under narrow sets of circumstances.
Reproducing those circumstances in a vendor lab requires an exact match of variables:

the same controller silicon and firmware binary,
the same NAND package and binning,
identical firmware/hardware configuration (DRAM vs HMB),
the same capacity and logical fill percentage,
precise workload pattern and queue depth,
similar thermal conditions and system platform firmware.

If any of these variables differs, a failure that happens on a consumer‑bench system could vanish in the lab — which explains how community tests can show reproducible failures while a vendor’s extensive tests show none. That does not automatically exonerate the update; it simply defines the forensic challenge.

Plausible technial technical mechanisms are consistent with the observed fingerprint and have precedent in storage incidents:

Exhausted SLC cache or squeezed spare‑block pool under sustained writes can force the controller into slower, more complex garbage collection and wear‑leveling activity; if a firmware path contains a ras on host behavior, the controller can hang or become unresponsive under that pressure.
HMB and DRAM differences matter: DRAM‑less designs that rely on Host Memory Buffer may be more sensitive to changes in host memory allocation timing. If a Windows update changes how HMB is negotiated or managed, it could alter controller timing windows.
Thermal stress: extended heavy writes generate heat; higher temperatures can exacerbate marginal firmware timing paths odependent fail‑safe logic. Phison’s recommendation of heatsinks implies thermal conditions are at least a plausible aggravating factor.
Aging NAND / wear state: drives with more program/erase cycles and lower spare pools can behave differently under stre and vendor labs often test new hardware rather than worn consumer drives.

All of these are plausible hypotheses that map to the available observations; none constitutes a definitive root cause without correlated controller telemetry and host traces.

The evidence landslimits

Strengths

Multiple independent labs converged on a similar workload and symptom profile, which increases confidence that the failure class is real for some configurations.
Phison’s public investigation andy collection elevated the issue from rumor to an active industry investigation — that matters for remediation cadence and credibility.

Limitations and open questions

No single d forensic post‑mortem with raw test artifacts, NVMe traces, or controller logs had been published at the time of Phison’s statement; the “4,500 hours” claim was reported by Phison but not accompanied by an audited test log in the imits independent verification.
Community reproductions often involve small sample sizes and bespoke benches; the sample is credible but not statistically representative of hundreds of millls.
The involvement of non‑Phison drives in some reproductions means attribution to one controller family alone is unlikely to be the full story; cross‑stack interactions are the more probable narrative.

Real user impact and data‑loss risk

The most important practical fact is straightforward: writes that fail while in flight can and r corrupted files for some users. In the worst reported cases an affected volume remained inaccessible without vendor‑level recovery. That means the incident carried a non‑zero data loss y‑write workflows performed on certain SSDs under certain conditions.
Because outcomes ranged from transient disappearance recoverable by reboot to permanent inaccessibility requiring RMA, the incident iorner‑case, high‑impact risk rather than a universal failure mode. The proper defense is conservative: backups, staged rollout, and if affected, immediate evidence preservation for vendor diagnosis.

Vendor and Microsoft posture

Phison: publicly acknowledged the investigation, reported extensive lab testing that failed to reproduce the crash, recommended thermal mitigation, and emphasized coordination with partners while disow that circulated in some channels.
Microsoft: said it was aware of reports and was collecting telemetry and feedback from affected users to diagnose the issue; at the time Microsoft reported no platform‑wide spike in disk failures driven by the update. Microsoft also invited users to submit Feedback Hub logs and to work with support to gather detaint posture has been coordination and cautious triage: vendors gather traces and telemetry, and Microsoft correlates host telemetry with vendor traces to isolate root cause and produce targeted mitigations.

Practical guidance — what owners and admins should do now

Short‑term actions for cetely. Copy important files to an external device or cloud service before performing large installs, patches, or bulk file moves. Backups are the single most effective mitigation.

Avoid long, sustained sequential writes on systems that have recently installed KB5063878 or KB5062660 until vendors confirm remediation. Examplestalls, cloning, or bulk media transfers.
Keep free space: where possible maintain a safety margin of free capacity (community guidance often cited keeping >40% free) because drive fill level materially affectd garbage collection behaviour.
Check SSD model, controller and firmware: use vendor utilities to capture model numbers, controller IDs and firmware revisions; record screenshots or logs for triage.

For enterprise administrators and fleet owners:

Stage KB5063878 in pilot rings that include representative hea DRAM‑less or HMB‑dependent modules; run sustained sequential write stress tests (50+ GB) on representative SKUs and firmware revisions before broad deployment.
Use WSUS/Intune to hold or rollback the update fntil vendor guidance confirms safety.
Maintain inventory mapping of SSD SKUs, controller families and firmware IDs to accelerate triage if a failure surfaces.

If you experience the issue:

Preserve evidence: capture WMe traces, SMART data, vendor utility dumps and Feedback Hub logs before rebooting where feasible; submit them to Microsoft and the SSD vendor. Imaging the affected drive imcovery options for vendor tools or professional recovery.

Why Phison might not reproduce the bug — plausible explanations

Phison’s failure to reproduce the field reports can be explained without denying those reports:

Test matrix mismatch: vendor labs often test new, out‑of‑box drivce platforms that may not include real‑world firmware variants, OEM‑applied module firmware or drives with long uat exist in the field.
Thermal and workload nuance: small differences in ambient temperature, mechanical cooling (heatsinkct workload cadence (short pauses, queue depths) can change whether an edge firmware path is hit. Phison’s heatsink guidance implicitly signals thermal sensitivity as a plausible aggravator.
Rare firmware/NAND permutations or counterfeit firmware: modules built by different integrators or with different NAND binnings can harbor aery narrow conditions.

All of these explain how a well‑resourced vendor can run thousands of test hours and still not reproduce a rare, workload‑dependent corner case experienced by a subset of users.

Possible remediation paths and expected timelines

Remediation typically follows one of two vectors:

Vendor firmware updates: if controller firmware is implicated, Phison and SSD vendors will craft targnd distribute validated images through SSD vendors; OEMs will integrate, test and publish firmware advisories per SKU. This is the usual fix path but may take days to weeks because of SKU validation requirements.
Microsoft mitigations: if host timing or driver-side behaviour is a major contributor, Microsoft caotfix or a temporary mitigation (or include a Known Issues entry in Release Health and provide guidance). Microsoft may also adjust servicing rings or telemetry to catch affected machines more quickly.

Expectaor advisories and validated firmware will likely be the primary long‑term solution; Microsoft’s role is to correlate telemetry and, if necessary, provide short‑term mitigations or update distribution controls.

What remains unverifiable and where caution is warranted

The exact cause‑and‑effect chain (i.e., a specific Windows code path deterministically causing controller state corruption) had not been published as a joint, auditable post‑mortem by Microsoft and SSD vendors at the time of Phison’s lab statement. That means definitive root‑cause attribution remained pending.
Phison’s announced test totals (cles) are vendor‑reported quantities; without raw logs or third‑party verification, those numbers are useful but not independently auditable. Readers should treat them as engineering claims rather than forensic proof.

In short, the absence of a public, joint post‑mortem with correlated host and controller logs means the comendor communications, independent reproductions and cautious operational controls until the parties publish a definitive technical analysis.

Broader lessons for Windows servicing and storage ecosystems

This episode is a textbook example of modern platform fragility. A single OS update can alter low‑level timing or memory allocation behaviour and thereby expose latent firmware bugs in storage controllers—bugs that remained dormant because prior host behaviour never stressed the same firmware paths. Two systemic lessons follow:

Expand pre‑release test matrices to include heavy‑write workloads and represB‑based modules. Real‑world heavy‑write profiling should be part of update validation, not an afterthought.
Improve structured telemetry and forensic exchange protocols between OS vendors and controller vendors so correlated NVMe traces and host logs can be shared quickly, auditable exchanges shorten mitigation windows and reduce user risk.

Until those process changes are broadly implemented, staged deployments and robust backup discipline will remain the most reliable defense against rare, high‑impact compatibility regressions.

dline that “Windows 11 update bricked SSDs” overstates the publicly available evidence at the time: vendor telemetry and Phison’s extended lab testing did not show a reproducible, universal failure across millions of drives, and Microsoft reported no platform‑wide telemetry spike.
At the same time, multiple independent labs and hobbyist test benches published a consistent, repeatable failure fingerprint — drives disappearing mid‑write under sustained sequential workloads when the target was partially full — and several user reports described real data corruption or inaccessible volumes. That makes the, narrow‑scope risk: not a mass recall, but a live compatibility concern that deserves forensic closure.
Best practice remains clear and unchanged: prioritize recent backups, stage updates in pilot rings that exercise heavy‑write workflows, avoid large sequely after installing the updates in question, and preserve forensic evidence (NVMe traces, SMART dumps, Feedback Hub logs) if you encounter the problem so vendors and Microsoft can correlate and fix it. Expect vendor firmware advisories and Microsoft mitigations as the likely resolution path; until then, treat the update and the implicated workload as a manageable but non‑negligible risk.

Source: PCMag UK Phison: We Found No Evidence Windows 11 Update Can Brick SSDs

ChatGPT · Aug 28, 2025

Microsoft’s August Windows 11 cumulative update has ignited a fraught, still‑unresolved investigation after community testers and some independent labs reported that sustained heavy write operations could cause certain NVMe SSDs to disappear from Windows — and, in a minority of cases, become inaccessible or suffer data corruption — while controller vendor Phison says its lab work could not reproduce the fault after thousands of hours of testing.

Background / Overview

The incident began after Microsoft shipped its August servicing wave for Windows 11 (commonly tracked in community reports as KB5063878, with a related preview package referred to in some posts as KB5062660). Within days, hobbyist testers and several specialist outlets published reproducible tests showing that continuous, large sequential writes — often described around the ~50 GB mark and performed to drives already substantially filled — could trigger a sudden disappearance of the target NVMe device from File Explorer, Device Manager and vendor utilities. Reboots sometimes restored visibility; in other cases drives remained inaccessible and files being written at the time were truncated or corrupted. (tomshardware.com)
Public attention coalesced around drives using certain Phison controller families, particularly DRAM‑less designs that rely on the NVMe Host Memory Buffer (HMB). That clustering prompted Phison to acknowledge it was “aware of industry‑wide effects” and to launch an extended investigation with Microsoft and SSD partners. Microsoft confirmed it was “aware of these reports” and began collecting telemetry and Feedback Hub reports from affected customers while running its own investigations. (bleepingcomputer.com)

What’s being reported (symptom fingerprint)

The trigger profile reported by multiple community testers: a sustained, large sequential write (examples include copying an entire game folder, extracting a single massive archive, or running a disk image restore), often when the SSD was >50–60% full. Failures tended to show up after tens of gigabytes of continuous writes.
The observed symptoms: mid‑write I/O errors followed by the target SSD disappearing from Windows enumeration (and sometimes BIOS/UEFI), vendor utilities failing to read SMART or controller telemetry, truncated files from the failed operation, and in a minority of cases, drives that did not return to service without vendor intervention or reflash.
Reproducibility: multiple independent hobbyist benches reported repeatable failure patterns under similar workloads, which elevated the reports from isolated anecdotes to an industry triage. However, reproducibility varied across specific SKUs, firmware revisions, motherboards, and BIOS versions.

Why this matters: the systemic risk

Modern NVMe SSDs are embedded systems whose reliability depends on precise coordination between the host OS storage stack, NVMe drivers, PCIe behavior, controller firmware, and NAND management (SLC caching, overprovisioning, garbage collection). A small change in host timing, buffer allocation or command ordering can exercise latent controller firmware bugs that remained dormant under prior host behavior. When the device disappears mid‑write, it can leave filesystem metadata in an inconsistent state and cause real data loss — not just inconvenience. For users and administrators who perform large file or imaging operations, this is a material risk until the root cause is resolved.

Phison’s investigation: thousands of hours, no repro

Phison — a major SSD controller vendor whose silicon is embedded in many consumer NVMe products — publicly published a brief summary of its validation work after being implicated in early collations of affected models. In its statement Phison reported dedicating more than 4,500 cumulative testing hours across roughly 2,200 test cycles focused on drives that were reported as potentially impacted, and said it was unable to reproduce the reported issue in its test environment. The company also stated that it had not received partner or customer RMA reports tied to the update during its testing period. (tomshardware.com)
Phison additionally warned about a falsified document that circulated early in the saga — a purported internal list of affected controllers that the company said was fabricated — and said it had taken steps to address misinformation. The vendor also offered general best‑practice guidance for high‑performance SSDs under extended workloads, such as using a proper heatsink or thermal pad to maintain optimal operating temperatures, although it did not connect thermal advice directly to reproducing the Windows‑update fault. (tomshardware.com) (tomshardware.com)

What Phison’s results mean — and what they don’t

Phison’s test campaign is meaningful: a controller vendor with access to silicon, sample hardware and internal diagnostics investing thousands of hours without seeing a reproduction strongly suggests the fault is conditional — dependent on a narrow combination of firmware revision, drive capacity/usage, platform firmware, NVMe driver variant, and workload. But an inability to reproduce a failure in-house does not categorically prove the field reports are false. Industrial labs can still miss environmental permutations (for example, a rare BIOS‑level interaction, specific data patterns, localized firmware customizations applied by OEMs, or particular background software) that occur in the wild. Independent community labs reported consistent reproduction steps, which is why Microsoft and vendors continue to coordinate triage.

Microsoft’s posture and telemetry

Microsoft has publicly said it is investigating the reports with its storage partners and has requested affected users to submit Feedback Hub logs and contact Support for the telemetry necessary to reproduce and diagnose the behavior. At the time vendors began public statements, Microsoft reported it had not detected a platform‑wide telemetry signal indicating an increase in disk failures linked to the update, and it could not reproduce a systemic issue in its internal testing. However, the company continues to gather diagnostic evidence and coordinate with SSD vendors to correlate host telemetry and controller logs. (bleepingcomputer.com)
This approach — cross‑stack telemetry correlation — is precisely what’s needed to move from anecdote to root‑cause: Microsoft can provide host‑side traces (kernel I/O patterns, HMB allocation timing, NVMe command streams), while controller vendors can supply firmware logs and internal error counters. Until these two data sets are jointly analyzed and a reproducible test case is validated across vendors, any conclusion about primary cause (host vs. controller) remains provisional.

Technical hypotheses (what engineers are focusing on)

Multiple independent analyses and vendor statements converge on two plausible, non‑exclusive mechanisms:

Host‑driven NVMe command or buffer regression
A Windows change could alter how page‑cache writes are staged, flushed, or ordered, changing DMA timing and NVMe command cadence. That altered cadence may expose latent firmware race conditions or unhandled controller states under heavy sustained writes. The symptom of the controller becoming unreadable at PCIe/NVMe level aligns with a controller hang scenario.
HMB / DRAM‑less controller fragility and metadata pressure
Many cost‑optimized consumer SSDs are DRAM‑less and rely on HMB to borrow host RAM for mapping tables and caching. Sustained sequential writes stress FTL (flash translation layer) and mapping structures; changes in host HMB allocation timing or lifecycle can surface resource exhaustion or race conditions in such firmware, especially when the drive is heavily used and SLC cache windows are reduced. Past Windows 11 updates have previously exposed similar HMB‑related fragility on select models, making this a credible hypothesis.

Neither hypothesis is proven; both remain consistent with the operational fingerprint reported by independent testers. Definitive attribution requires paired host and controller forensic logs.

Cross‑checking the evidence: independent sources

Key community reproductions and specialist outlets have produced consistent test recipes and results, while vendor and Microsoft statements have provided partial counterpoints. Independent verification across at least two reputable sources supports the central claims:

Reproducible community tests showing device disappearance during sustained writes were reported and aggregated by multiple hardware outlets and test benches. (tomshardware.com)
Phison publicly confirmed an investigation and later published a validation summary citing thousands of test hours without reproduction. (tomshardware.com) (tomshardware.com)
Microsoft stated it was “aware” and investigating with partners while reporting no clear telemetry spike at the time of initial vendor statements. (bleepingcomputer.com)

Together, these independent threads show a real signal in community labs and a cautious, data‑driven response from vendors and Microsoft. The inconsistency between hands‑on repros and vendor lab results points to a complex cross‑stack interaction rather than a simple, reproducible “one‑button bricking” bug.

Practical, immediate guidance (what users and admins should do now)

The safest posture until vendors or Microsoft publish validated guidance is conservative and backup‑focused.

Back up now. Create verified copies of critical data to an external drive or the cloud before performing large writes. Backups are the only reliable protection against unexpected mid‑write failures.
Avoid heavy sequential writes on machines that received the August update until you’ve validated firmware and platform guidance. Split large transfers into smaller batches if feasible.
If you manage fleets: stage the update in a test ring that includes representative storage hardware and run sustained large‑write workloads before broad deployment. Use Microsoft’s deployment controls to pause or rollback the update where risk is unacceptable.
Check your SSD vendor’s support page and official utilities (Corsair iCUE, SanDisk Dashboard, Kioxia/Crucial tools) for firmware advisories — if a vendor releases a firmware patch validated for your SKU, apply it only after backing up. Firmware fixes usually arrive through drive makers, not the controller vendor directly.
If a drive disappears mid‑write: stop writing to the system. Don’t initialize or reformat the disk. Capture system logs and vendor utility outputs, then create a forensic, read‑only image if the drive remains inaccessible and you need to preserve evidence for vendor RMA or recovery.

These steps prioritize preventing irreversible data loss and preserve the forensic artifacts vendors need to diagnose the issue.

Strengths of the current response — and the gaps

Strengths

Rapid community triage produced repeatable test recipes that made vendor investigation feasible and focused.
Phison’s public testing campaign and Microsoft’s telemetry gathering demonstrate the major platform stakeholders are engaged and collecting data. (tomshardware.com) (bleepingcomputer.com)

Gaps and risks

No single vendor or Microsoft has yet published a full, joint root‑cause analysis correlating host traces with controller logs. That means attribution remains provisional.
Variability across firmware SKUs, OEM configurations, BIOS revisions and platform drivers makes a universal reproduction test difficult; industrial labs can miss specific field permutations.
The absence of a widespread RMA spike (per vendor statements) does not eliminate the risk to individual users who face real data loss. The incident highlights the asymmetry: rare events can be catastrophic for affected users even if statistically small across the installed base.

What to watch next (evidence signals that will resolve the question)

Joint Microsoft + controller vendor post‑mortem: a coordinated, auditable analysis that ties host‑side traces to controller logs and reproduces the failure in a lab using vendor tooling.
Firmware advisories and vendor‑validated firmware builds for specific branded SKUs distributed by SSD manufacturers and documented test results.
Microsoft release‑health updates or a Known Issue Rollback (KIR) if a host‑side mitigation is required.
Verified field RMA statistics showing an uptick tied to the update across multiple vendors, which would indicate a larger‑scale problem beyond isolated repro benches.

When any of these appear, they should be treated as turning points: joint telemetry correlation and a distributed firmware patch are the most likely pathway to closure.

Analysis and measured conclusion

This episode is a textbook example of modern storage‑stack fragility: the system behavior that users rely on is a co‑engineered product of OS, drivers, platform firmware and controller microcode. The early community reproductions — consistent workload recipes that produce identical failure fingerprints — are a serious signal and the right reason for Microsoft and Phison to engage. Phison’s extensive internal testing and inability to reproduce the fault are also meaningful and reduce the likelihood of a single, simple root‑cause that applies universally. (tomshardware.com)
The plausible technical explanation is an interaction: a change in host I/O behavior introduced by the Windows update that, under a narrow combination of drive fill level, controller firmware revision and platform conditions, can push some controllers into an unrecoverable state. That class of bug is tricky — it can be prolific in community benches yet rare in vendor telemetry. Until a joint forensic report is published, the prudent stance for users and admins is conservative: back up, avoid sustained large writes on updated systems where possible, and follow vendor guidance.
Finally, the incident reinforces two perennial lessons for Windows users and IT teams:

Backups are not optional: when low‑level storage metadata is at risk, an up‑to‑date, tested backup is the only reliable recovery tool.
Test rings must include storage stress tests: staging updates against representative hardware and heavy‑write workloads is essential to catch rare but high‑impact regressions before broad deployment.

This remains an active, evolving story. Watch for coordinated vendor advisories, Microsoft release‑health updates, and firmware tooling from SSD manufacturers — those are the signals that will move the situation from investigation to remediation.

Source: TechRadar Microsoft is still looking into that nasty SSD bug - but its partner’s drawing a blank

Navigation section

Windows 11 Aug 2025 KB5063878: SSDs Vanish Under Heavy Writes

What the reports show​

Symptom profile: the consistent failure signature​

Typical trigger parameters identified in tests​

Which drives and controllers are implicated (and how reliable the lists are)​

What Microsoft and vendors have said so far​

Technical analysis: what could be happening​

Immediate practical advice for Windows 11 users (what to do right now)​

Guidance for IT administrators and organizations​

Recovery and data-recovery realities​

Critical analysis: strengths and limitations of the current evidence​

What to expect next​

Final verdict and conclusion​

AI

Background​

How the fault was first reproduced (what testers did)​

Symptoms observed​

Which drives are implicated — and what we know about scope​

Vendor and platform responses​

Technical analysis — what most evidence points to​

Immediate guidance for end users (practical, prioritized)​

Recommended steps for IT administrators​

Recovery prospects and when to escalate to data recovery professionals​

Strengths and weaknesses of the current response​

Longer-term implications and lessons for users and vendors​

Final assessment and practical takeaway​

AI

Background / Overview​

What users are actually seeing: the symptom fingerprint​

Typical trigger profile​

Common workload characteristics reported by testers​

Which drives and controllers are implicated?​

Verified technical anchors (what we can confirm today)​

Why this matters: the risk to your data​

Vendor responses and where the investigation stands​

Practical, immediate guidance for Windows users (do this now)​

Recovery options and data rescue — what to consider​

Technical analysis: plausible mechanisms and why this can happen​

Broader implications for Windows servicing, testing and enterprise rollouts​

Strengths and weaknesses of current reporting​

What to watch next​

Conclusion​

AI

Background / Overview​

What users and test benches are seeing​

Symptom profile (short)​

Trigger parameters reported in independent reproductions​

Which drives and controllers are implicated (and the caveats)​

Technical analysis — what could be happening​

Reproducibility and conflicting test results​

How worried should you be?​

Immediate precautions and mitigation steps​

If your drive has already failed — recommended recovery checklist​

What Microsoft and vendors have said (status as of early reporting)​

Guidance for IT administrators and power users​

What to watch for next​

Final assessment — strengths and risks​

Bottom line​

AI

Background / Overview​

What’s being reported: the observable symptoms​

The failure fingerprint​

Practical reproduction thresholds reported by testers​

Who’s involved and what they’ve said​

Microsoft​

SSD controller vendors and manufacturers​

Community researchers and independent test benches​

Technical analysis: plausible mechanisms​

Which drives are at risk — and how reliable are the lists?​

Real‑world consequences observed so far​

Immediate, practical mitigations​

How to roll back and the SSU complication​

Vendor coordination, false documents, and information hygiene​

Recovery options for affected systems​

Balancing risk: security vs. stability​

Why this matters: structural lessons for storage reliability​

Timeline and what to watch next​

Conclusion​

AI

What the reports show

Symptom profile: the consistent failure signature

Typical trigger parameters identified in tests

Which drives and controllers are implicated (and how reliable the lists are)

What Microsoft and vendors have said so far

Technical analysis: what could be happening

Immediate practical advice for Windows 11 users (what to do right now)

Guidance for IT administrators and organizations

Recovery and data-recovery realities

Critical analysis: strengths and limitations of the current evidence

What to expect next

Final verdict and conclusion

Background

How the fault was first reproduced (what testers did)

Symptoms observed

Which drives are implicated — and what we know about scope

Vendor and platform responses

Technical analysis — what most evidence points to

Immediate guidance for end users (practical, prioritized)

Recommended steps for IT administrators

Recovery prospects and when to escalate to data recovery professionals

Strengths and weaknesses of the current response

Longer-term implications and lessons for users and vendors

Final assessment and practical takeaway

Background / Overview

What users are actually seeing: the symptom fingerprint

Typical trigger profile

Common workload characteristics reported by testers

Which drives and controllers are implicated?

Verified technical anchors (what we can confirm today)

Why this matters: the risk to your data

Vendor responses and where the investigation stands

Practical, immediate guidance for Windows users (do this now)

Recovery options and data rescue — what to consider

Technical analysis: plausible mechanisms and why this can happen

Broader implications for Windows servicing, testing and enterprise rollouts

Strengths and weaknesses of current reporting

What to watch next

Conclusion

Background / Overview

What users and test benches are seeing

Symptom profile (short)

Trigger parameters reported in independent reproductions

Which drives and controllers are implicated (and the caveats)

Technical analysis — what could be happening

Reproducibility and conflicting test results

How worried should you be?

Immediate precautions and mitigation steps

If your drive has already failed — recommended recovery checklist

What Microsoft and vendors have said (status as of early reporting)

Guidance for IT administrators and power users

What to watch for next

Final assessment — strengths and risks

Bottom line

Background / Overview

What’s being reported: the observable symptoms

The failure fingerprint

Practical reproduction thresholds reported by testers

Who’s involved and what they’ve said

Microsoft

SSD controller vendors and manufacturers

Community researchers and independent test benches

Technical analysis: plausible mechanisms

Which drives are at risk — and how reliable are the lists?

Real‑world consequences observed so far

Immediate, practical mitigations

How to roll back and the SSU complication

Vendor coordination, false documents, and information hygiene

Recovery options for affected systems

Balancing risk: security vs. stability

Why this matters: structural lessons for storage reliability

Timeline and what to watch next

Conclusion

Background / Overview

How the failures present in the field

Symptom profile (what users and testers report)

Workload and trigger characteristics

Which drives and controllers appear overrepresented

Technical primer: why an OS update can break a drive

Vendor and platform responses