Windows 11 KB5063878 Storage Fault: Drives Vanish Under Heavy Writes

Microsoft’s August cumulative for Windows 11 — KB5063878 (OS Build 26100.4946) — has been linked by independent testers and enthusiast communities to a reproducible and severe storage fault: under sustained large sequential writes (reports center around the 50 GB range), certain NVMe SSDs—and a small number of HDDs—can become completely unresponsive, disappear from the operating system, and present unreadable SMART data, sometimes resulting in file-system corruption and permanent data loss. Early testing points to a pattern that over-represents Phison-based controllers, particularly DRAM‑less or older controller families, but the phenomenon has not been limited to a single vendor or firmware, and Microsoft has not published an official storage-related known‑issues bulletin tied to the update at the time of reporting. (support.microsoft.com)

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Background​

What KB5063878 is and how it was released​

KB5063878 was published by Microsoft on August 12, 2025 as a combined servicing stack and cumulative security update for Windows 11 version 24H2 (OS Build 26100.4946). The official release notes describe security and quality improvements and list no currently known issues in the Microsoft support entry for the KB. Administrators, however, quickly encountered an unrelated deployment regression (WSUS/SCCM install failures with error 0x80240069) that Microsoft subsequently addressed through its servicing controls. (support.microsoft.com) (bleepingcomputer.com)

Why this matters now​

Storage reliability is a single point of failure for most users and organizations. An OS-level change that manifests as drives disappearing mid-write is not merely a performance nuisance — it is a direct data‑integrity risk. The combination of an urgent security rollup and widespread background updates means devices recently patched are at potential risk precisely when they perform heavy write workloads (game updates, large installers, backups), which is how many users discovered the issue. Community reproductions and tech outlets picked up the initial findings within days of the KB’s rollout. (wccftech.com)

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What the reports show — symptoms and reproducibility​

Core symptoms observed by testers​

• Drives disappear from Windows (Device Manager and Disk Management: no device present) while write operations are in progress.
• SMART and controller attributes become unreadable by the OS during the failure state.
• In some cases a reboot briefly restores visibility, but the failure often recurs under the same workload and may leave behind file-system corruption.
• The trigger is described consistently as sustained sequential writes on the order of tens of gigabytes (community tests often cite ~50 GB as the threshold) and elevated controller utilization (reports note controller usage spikes above ~60%). (notebookcheck.net)

How reproducible is the issue?​

Independent community testing by enthusiasts and a handful of aggregation threads show reproducible behavior on specific systems when the same write pattern is applied, but results are not universal across all models or firmware versions. The signal is strong enough that multiple outlets and communities have collated lists of candidate models and controller families, but vendor‑level telemetry and a Microsoft acknowledgement of the storage symptom set are not yet public at scale. That leaves the current state as an urgent community warning rather than a fully confirmed, vendor‑validated root cause. (notebookcheck.net)

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Which drives and controllers have been implicated?​

Models and controllers flagged in early reports​

Community lists assembled from hands‑on testing and aggregator sites include drives and controllers such as:

• Phison PS5012‑E12 / Phison E16 family (examples: Corsair Force MP600, other E12‑based models), and some E31T/E21T variants.
• Kioxia Exceria Plus G4 (Phison‑based SKU variants).
• SanDisk Extreme PRO M.2 NVMe 3D (Triton MP28 controller — included in some aggregated lists).
• Fikwot FN955 and other third-party branded devices reported in initial threads.
• Additional models (WD Blue SN5000, WD Red SA500) were mentioned in follow-ups as sometimes recovering after reboot. (notebookcheck.net) (wccftech.com)

Important caveats about the model lists​

• These lists are community‑compiled and unofficial. They are useful signals, not definitive diagnostic inventories. Firmware version, system firmware (BIOS/UEFI), driver stack, platform-specific NVMe driver variants, and workload patterns all influence whether a drive will fail under these conditions. Multiple sources emphasize that no single vendor or firmware uniformly accounts for every report. Treat the lists as investigation starting points rather than a final compatibility matrix.

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Technical analysis — likely root causes and mechanics​

Two dominant hypotheses​

• Operating‑system / kernel‑level regression: a Windows kernel or driver change in how it handles buffered/sequential writes (or NVMe/HDD I/O paths) that leads to command sequences or timing that trigger latent firmware bugs in some controllers. This pattern would explain why seemingly unrelated drives from different vendors behave similarly under identical host conditions.
• Controller/firmware edge case triggered by host behavior: SSD controllers (notably some Phison families) can contain latent bugs that only manifest under specific sustained loads or host‑provided resources (e.g., Host Memory Buffer interactions for DRAM‑less drives). An update that subtly changes timing, caching, or memory allocation may push a controller into a crash or lock‑up state, causing the device to disappear from the host. Historical precedence exists for HMB‑related instability in Windows 11 24H2 rollouts (previous incidents in late 2024 and 2025 required vendor firmware fixes and Microsoft upgrade blocks).

Why SSDs can “disappear”​

When a controller locks up or its firmware crashes, the NVMe device can stop responding to standard admin/scsi/PCIe queries. The operating system cannot read SMART, cannot enumerate namespaces, and will report the device as absent. From a host perspective that’s indistinguishable from a device that has been physically removed. In certain failure modes, a reboot briefly reinitializes the controller and restores access; in worse cases the controller state or firmware corruption prevents recovery without vendor intervention.

HMB and DRAM‑less SSDs: why they’re sensitive​

DRAM‑less controllers rely on the Host Memory Buffer to cache mapping tables. HMB tight-couples host memory allocation and controller behavior; subtle changes in how Windows assigns or uses HMB memory can expose timing or capacity bugs in firmware. Previous Windows 24H2 episodes showcased this exact coupling — firmware patches and Microsoft-side mitigations were used to restore stability. The present symptoms echo that architecture‑level fragility even if HMB is not definitively the root cause in all cases.

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Verification status: what’s confirmed and what remains unproven​

Confirmed facts​

• Microsoft released KB5063878 on August 12, 2025 (OS Build 26100.4946). The official KB page lists the update and no current known issues for storage. (support.microsoft.com)
• The same cumulative produced widely reported enterprise delivery failures (WSUS/SCCM) with error 0x80240069, which Microsoft acknowledged and mitigated. (bleepingcomputer.com)

Reported but not yet vendor‑validated​

• Multiple independent community reports indicate that sustained large writes can cause drives to disappear and SMART data to be unreadable; affected models are over‑represented by Phison controller families. Those reports are corroborated by several outlets that aggregated community testing, but Microsoft and most SSD vendors had not universally confirmed a causal link when these accounts circulated. These remain high‑priority hypotheses that require vendor telemetry and Microsoft analysis to confirm root cause. (wccftech.com)

What to watch for in the coming hours/days​

• Vendor firmware advisories or coordinated statements (Corsair, Phison, Kioxia, SanDisk, WD) that identify specific firmware versions or recommend mitigations.
• Microsoft Release Health / known‑issues updates that add storage symptoms to the KB entry or announce an upgrade block for certain models.
• Wider telemetry: a dramatic rise in RMA requests or vendor service bulletins would move the issue from localized anecdotes to a confirmed systemic regression.

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Practical guidance — immediate steps for users and administrators​

For home users and enthusiasts (short checklist)​

• Back up critical data immediately to an external device or cloud. Data backups are the only guaranteed insurance against drive-level failures. Do this before performing any further writes or firmware flashes.
• If you have recently installed KB5063878 and you rely on an SSD that matches early suspect lists (Phison controllers, DRAM‑less SKUs), avoid large sustained writes (no mass game installs, large game patches, bulk copies, or large video exports) until you can confirm vendor guidance or Microsoft updates. (notebookcheck.net)
• Check your SSD vendor’s management tool for firmware updates and guidance. Do not flash firmware on a device containing critical data unless you have a verified backup and the vendor explicitly recommends the specific update.

For IT administrators and procurement teams​

• Inventory: map SSD models, controller families, and firmware levels across endpoints. Prioritize identifying DRAM‑less NVMe devices or drives previously associated with 24H2 issues.
• Pause deployment: use WSUS/SCCM/MECM or MDM controls to withhold KB5063878 from at‑risk endpoints until vendor guidance is verified. Microsoft’s Known Issue Rollback (KIR) has been used previously to mitigate install regressions; apply enterprise controls prudently. (bleepingcomputer.com)
• Schedule heavy I/O tasks (imaging, large file distribution, backups) to systems not yet patched or to known‑good hardware to avoid inadvertent failures.

If a drive becomes unreadable​

• Power off the host immediately. Continued power cycles or stress tests can worsen firmware corruption.
• If the data is critical, remove the drive and attach it to a quarantine system (forensic imaging recommended) rather than attempting filesystem repairs or reformatting. Imaging preserves what remains for vendor or lab analysis.
• Collect system logs (Event Viewer System/Application), capture NVMe driver logs, and note exact firmware versions and timestamps for vendor RMA. Vendors may require logs for root‑cause analysis.

Registry and HMB mitigations — approach with caution​

Community‑proposed registry mitigations (disabling or limiting HMB) were used during prior 24H2 episodes to reduce risk, but they are workarounds that reduce SSD performance and are not fixes. Apply such mitigations only after lab testing and with documented rollback procedures; do not deploy them broadly without vendor and internal QA approval.

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Critical analysis — strengths, risks, and who bears responsibility​

Strengths in the ecosystem response​

• Microsoft’s servicing architecture (KIR and re‑release mechanisms) provides avenues to quickly mitigate distribution regressions in enterprise channels, as demonstrated with the WSUS/SCCM issue. Vendors can also issue targeted firmware updates when root cause points to controller firmware. (bleepingcomputer.com)

Systemic weaknesses and recurring patterns​

• The Windows storage stack and modern SSD firmware interact in complex, timing‑sensitive ways. The diversity of controller implementations and firmware revisions makes exhaustive pre‑release testing practically impossible at scale; edge cases will continue to appear unless testing expands to encompass a broader set of real‑world I/O patterns. Several recent episodes (including the earlier 24H2 HMB problem) show a repeating failure mode: an OS change surfaces a latent firmware bug. That model produces difficult forensic work and a contentious blame game between OS and hardware manufacturers.

Risk to end users​

• Data integrity risk is the highest impact. When drives “disappear” mid‑write, file systems can be left inconsistent. Reboots may render the drive visible again but not restore lost or corrupted files. For users without recent backups, the economic and emotional cost of data loss is high.

Who should be held accountable?​

• Accountability is shared: Microsoft must validate OS‑side regressions and, where necessary, provide rapid mitigations or upgrade blocks; SSD vendors must make firmware that tolerates reasonable host behavior and publish clear firmware guidance. The most constructive path is cooperative: vendor firmware updates or a Microsoft driver/stack adjustment will likely be the technical fix, and both parties should be transparent with telemetry and guidance. Historically, that cooperative remediation model has resolved similar incidents.

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What to expect next​

• Vendor firmware advisories or targeted firmware updates for implicated controller families (if root cause is in firmware).
• Microsoft Release Health updates and, if necessary, an official Known Issues entry for KB5063878 that addresses storage behavior or recommends upgrade blocks for specific hardware IDs.
• Wider forensic reporting from independent storage analysts if the problem proves reproducible across a broader sample — that reporting would escalate RMA volumes and public vendor statements.

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Immediate checklist (recommended actions)​

• Back up critical data now to a different physical device or cloud.
• If KB5063878 is installed and you have at‑risk hardware (Phison or DRAM‑less NVMe), do not perform large sustained writes until you have vendor guidance. (notebookcheck.net)
• Check vendor firmware utilities and only apply vendor‑recommended firmware after backing up.
• Administrators: inventory and use update management tools to withhold KB5063878 from impacted fleets until validated.
• If a drive fails: power off, image the drive (for forensics), collect logs, and contact vendor support with detailed evidence.

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Conclusion​

The KB5063878 reports are an urgent community signal that should be treated seriously. While Microsoft’s official KB page currently lists no storage‑related known issues, independent reproductions and aggregated reporting suggest a plausible and dangerous regression that disproportionately affects certain controller families under sustained heavy writes. The responsible posture for users and IT teams is pragmatic: back up data, avoid heavy writes on recently patched systems with suspect SSDs, and wait for coordinated vendor or Microsoft guidance before resuming normal I/O patterns. Cooperative remediation between Microsoft and SSD vendors has resolved similar crises in the past; the priority now is rapid, transparent investigation and clear guidance to prevent further data loss. (support.microsoft.com) (wccftech.com)

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Source: igor´sLAB Windows 11 update “KB5063878” destroys SSDs: Storage error with large amounts of data, Phison controller particularly affected | igor´sLAB

 

[ChatGPT]

Microsoft’s staggered Windows 11 24H2 rollout has tripped a serious compatibility landmine: scattered but reproducible reports show that one recent cumulative update can cause some NVMe SSDs to become unresponsive or vanish during sustained large writes, and earlier instances of the 24H2 feature update also produced BSODs for certain Western Digital drives. The practical result for affected users has ranged from repeated Blue Screen of Death (BSOD) crashes to drives temporarily disappearing from Device Manager and, in a minority of reports, files written during the failure window becoming corrupted or inaccessible. (support.microsoft.com)

Background: two related problems, one unsettling pattern​

The headlines conflate a pair of related but distinct incidents. First, the original Windows 11 24H2 feature rollout (late 2024) produced an outbreak of BSODs and installation blocks tied to how the OS allocated Host Memory Buffer (HMB) to DRAM‑less NVMe SSDs — notably Western Digital SN770 and SN580 models in many community threads. That episode produced user‑level workarounds and vendor firmware updates. (answers.microsoft.com, reddit.com)
Second, a mid‑August 2025 cumulative update — combined servicing stack and LCU identified as KB5063878 (OS Build 26100.4946) — was published by Microsoft on August 12, 2025 and subsequently associated by independent testers with a storage regression: under sustained, large sequential writes (community repros commonly cite ~50 GB or more), some NVMe SSDs may stop responding, disappear from the OS topology, and present unreadable SMART/controller telemetry. Microsoft’s KB page lists the update and its build number but initially did not list a storage‑device failure as a known issue; community telemetry and vendor diagnostics have driven the public discussion. (support.microsoft.com, windowsforum.com)

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How the failures present in practice​

Typical symptoms reported by users and testers​

• Sudden disappearance of an SSD from Device Manager and Disk Management while a large file transfer or game install is in progress.
• Event Viewer entries showing storage controller or NVMe errors, or an abrupt stall that may be followed by a reboot.
• SMART attributes or controller telemetry becoming unreadable to vendor utilities and diagnostic tools after the incident.
• Reboot sometimes temporarily restores visibility, but files written during the incident can be corrupted or missing in a subset of reports. (windowsforum.com, tomshardware.com)

Which drives seem to show the pattern?​

Community collations point to clusters of affected drives rather than a single brand or model. Early reproductions often highlighted drives using certain Phison controller families and many DRAM‑less NVMe designs; Western Digital SN770/SN580 appeared prominently in the earlier 24H2 feature‑update failures. That said, model lists vary between testers and firmware state, and not every drive of a given model is affected. Treat these community lists as investigative leads rather than definitive recall lists. (windowsforum.com)

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Technical explanation — plausible mechanisms (what the evidence suggests)​

At a high level, the failure fingerprint points to an interaction between the host OS storage stack, drivers, and SSD controller firmware under sustained, heavy writes. Three plausible mechanisms recur in technical analyses and community reproductions:

• Host Memory Buffer (HMB) allocation changes — When Windows adjusts the amount of host RAM used for SSD caching, some DRAM‑less controllers can be pushed into edge conditions they cannot handle. In the earlier 24H2 feature update, increased HMB allocations (for example, drives requesting or being assigned larger cache windows) were implicated in BSODs for specific WD models. (answers.microsoft.com)
• Buffered I/O or NVMe command timing regressions — A small change in kernel buffering, command ordering, or timing can expose latent firmware bugs. Under sustained sequential writes the SSD controller’s internal metadata updates and mapping tables face heavy stress; altered host behavior can produce a controller hang that makes the device look “removed” from the PCIe/storage topology. (windowsforum.com)
• Controller firmware edge cases under high utilization — Controller families differ in how they handle bursts, mapping updates, wear‑leveling, and error recovery. Community repros frequently identify similar controller families (Phison variants) but also note that several non‑Phison drives have surfaced in isolated reports — indicating the OS stack change is a probable cofactor rather than a single‑vendor firmware bug. (windowsforum.com)

Important technical caveat: conclusive root‑cause attribution requires telemetry from affected SSD vendors and Microsoft. Community reproductions and vendor tools are powerful for hypothesis building, but they are not a substitute for vendor/Microsoft diagnostic telemetry. Several vendor dashboards and updated firmware packages have been issued in response to the earlier 24H2 problem, illustrating that fixes can be firmware‑level, OS‑level, or a combination.

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What Microsoft and vendors have said and done so far​

Microsoft’s official KB entry for KB5063878 confirms the update and build number and lists general improvements; at publication it did not list storage failures as a known issue. Independent reporting and community telemetry then highlighted the storage regression, prompting further investigation by vendors and Microsoft. Microsoft has used staged rollout controls and Known Issue Rollback (KIR) mechanisms in other regression cases; similar servicing controls may be applied while the plateau of reports is assessed. (support.microsoft.com, windowsforum.com)
Western Digital and other SSD vendors have engaged with affected communities and, in earlier 24H2 events, issued firmware updates for specific models. Those firmware interventions resolved many but not all user reports; in some cases users combined firmware updates with host registry workarounds or rolled back the OS version to regain stability. Vendor firmware updates remain the recommended long‑term remediation when available.

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Practical guidance for users and IT admins — triage, mitigation, recovery​

The situation is time‑sensitive and workload‑dependent. The following checklist synthesizes vendor guidance, Microsoft update mechanics, and community mitigations.

Immediate consumer checklist​

• Pause large sequential writes (game installs, disk cloning, media migrations) on systems that have installed the August 12, 2025 cumulative update or earlier suspect 24H2 builds until you confirm firmware compatibility. Community repros commonly cite ~50 GB sustained writes as a trigger. (windowsforum.com)
• Back up important data now. If a drive shows signs of instability, copy vital data to a known‑good device or cloud storage immediately. The risk of corrupted or missing files increases with repeated attempts to reproduce the failure. (windowsforum.com)
• Check vendor tools and firmware: Launch your SSD vendor utility (WD Dashboard, Samsung Magician, Crucial Storage Executive, Corsair Toolbox, etc.) and verify firmware levels. If a firmware update is available for your model, follow vendor instructions carefully and backup beforehand. (windowsforum.com, reddit.com)
• Avoid forced OS updates or clean installs that bypass Microsoft’s staged checks until vendors signal compatibility fixes; installation assistants or Media Creation Tool upgrades can install versions that trigger device checks or behaviors that are still under investigation.

Power‑user or emergency mitigations​

• Registry HMB mitigations (advanced, risky): Community scripts and registry adjustments that limit or disable HMB allocation have reduced BSOD loops following the 24H2 feature update for some WD models. These are emergency measures and can reduce SSD performance. Only use them with a full backup and careful instructions. Treat registry edits as temporary stop‑gaps.
• Temporarily revert the update: If the system is unstable and vendor guidance isn’t available, rolling back to the last stable OS build can restore functionality. Follow the official Windows rollback paths and accept that some security/quality fixes will be missed until a corrected package is available. (support.microsoft.com)

Enterprise / IT admin checklist​

• Halt large‑scale deployments via WSUS/SCCM until vendor compatibility lists and Microsoft release health guidance are clear. Microsoft has previously used Known Issue Rollback (KIR) to address deployment‑specific regressions. (windowsforum.com)
• Monitor Windows Release Health and vendor advisories for flagged device blocks or targeted mitigations. Use staged ring deployments (pilot → broader rollouts) and delay mass patching on mission‑critical systems. (support.microsoft.com, windowsforum.com)
• Gather forensic artifacts from affected machines: Event Viewer logs, Disk Management snapshots, vendor diagnostic logs, and SMART dumps are crucial in coordinating with vendors and Microsoft for root‑cause analysis. (windowsforum.com)

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Risk assessment and industry implications​

Strengths in the current response​

• Rapid community detection and reproduction: Enthusiast and enterprise testers reproduced symptoms quickly and shared diagnostic patterns, which accelerated vendor and Microsoft awareness. Community telemetry and test artifacts often surface edge cases before large‑scale telemetry does.
• Vendor firmware agility: Some SSD vendors issued firmware updates promptly in prior incidents, showing that controller vendors can address firmware edge cases when properly diagnosed. (reddit.com)

Notable weaknesses and risk vectors​

• Staged rollouts can obscure edge‑case regressions: Microsoft’s staged delivery is intended to catch regressions, but environment‑specific code paths (WSUS/SCCM, OEM driver stacks) can delay detection or create scattered impact footprints that are difficult to measure rapidly. This complicates communications and trust. (windowsforum.com)
• Registry and user‑level workarounds are precarious: The prevalence of registry hacks and third‑party scripts as stop‑gaps is a symptom of a gap in official mitigations. These workarounds can reduce performance, introduce stability risks, and place the burden of recovery on consumers and IT staff.
• Unclear scale and long‑term data integrity risk: Because reports are scattered across forums and tests, the true failure rate and whether any drives experienced irrecoverable wear or permanent loss remains uncertain. Until vendors and Microsoft publish consolidated telemetry and analysis, the scale of the risk is an estimate. Flagging this uncertainty is essential.

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What a rigorous fix should include (technical blueprint)​

A robust remediation should be multi‑pronged and transparent:

• Coordinate telemetry: Microsoft, SSD vendors, and OEMs should share anonymized telemetry and test vectors that reproduce the failure in controlled environments. This helps isolate whether the cause is HMB policy misallocation, NVMe command ordering changes, or a controller timing sensitivity. (windowsforum.com)
• Deliver targeted mitigations: If the fault is OS‑side, Microsoft can issue a targeted servicing rollback or patch (KIR-style) that prevents the problematic behavior on affected models while preserving the broader security LCU. If the fault is firmware‑side, vendors should push clear firmware advisories and automatic updates via vendor dashboards. (windowsforum.com)
• Improve pre‑release compatibility testing: Expand compatibility matrices and stress tests (sustained sequential writes, controller saturations) in Windows update certification processes to catch firmware edge cases before broad rollouts. Vendors should ship explicit compatibility markers so the OS can block risky upgrades until firmware updates are applied.
• Communicate clearly with end users and admins: Transparent release notes, clear flags in Windows Update (e.g., “update blocked for this device due to storage firmware compatibility”), and step‑by‑step recovery guides will reduce risky user behavior and help admins manage the patch cycle.

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Quick reference — do this now (concise action list)​

• Stop heavy writes on machines that have applied the August 12, 2025 cumulative update if you use NVMe/SSD for critical storage. (windowsforum.com)
• Back up critical data immediately to an external device or cloud. (windowsforum.com)
• Check your SSD vendor tool for firmware updates; apply vendor‑recommended firmware only after backing up. (reddit.com)
• If you experience BSOD loops tied to HMB allocation after the 24H2 feature update, consider vendor firmware, official Windows rollback paths, or coordinated vendor/MS mitigations rather than permanent registry hacks. Registry changes are emergency-only.

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What remains unverified and why caution is needed​

• The exact prevalence of permanent data loss versus temporary unresponsiveness is not publicly quantified. Community reports include both recoverable and unrecoverable outcomes, but there is no consolidated public telemetry that enumerates affected devices, firmware versions, or failure rates. Until vendors or Microsoft publish unified diagnostics, scale estimates should be treated cautiously.
• Claims that a specific controller family is the sole root cause are premature. Community collations point to Phison‑based controllers frequently, but isolated reports span multiple controller vendors. The most defensible technical claim is that a host OS change exposed firmware sensitivities in certain controllers under heavy sequential write loads. (windowsforum.com)

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Final analysis — what this episode means for Windows users​

The incident is a timely reminder that operating system updates do more than add features: they change how the OS interacts with hardware at a low level. In an era when SSD designs increasingly rely on host cooperation mechanisms like HMB, small changes in allocation policy, buffering, or command timing can cascade into firmware edge cases. The long‑term fix will likely be a combination of targeted OS mitigations, vendor firmware updates, and improved pre‑release stress testing.
For end users and admins, the practical takeaways are clear: prioritize backups, verify firmware/driver compatibility before mass updates, and apply staged deployment practices for mission‑critical systems. Where vendor updates are available, apply them; where vendor or Microsoft guidance is pending, prefer caution over haste. The issue is fixable, but the path requires coordinated telemetry, crisp communication, and restraint from blunt stop‑gaps that trade stability for performance.
Conclusion: the reports are serious and actionable for users who perform heavy writes or run affected hardware, but they remain a mixed bag of reproducible failure modes, targeted vendor fixes, and community workarounds. The best immediate defense is cautious updating, disciplined backups, and close tracking of vendor and Microsoft advisories as they publish verified, targeted fixes. (support.microsoft.com, windowsforum.com)

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Source: TechRadar Reports of Windows 11 update breaking some SSDs are scattered - but they make me nervous
Source: TechPowerUp Microsoft Windows 11 24H2 Update May Cause SSD Failures

 

[ChatGPT]

A Windows 11 cumulative update released on August 12, 2025 — KB5063878 (OS Build 26100.4946) — has been linked by multiple community tests and specialist outlets to a potentially serious storage regression that can make some NVMe SSDs disappear from the operating system during large, sustained writes, risking data corruption and loss. rview
Microsoft shipped KB5063878 as the August cumulative security and quality rollup for Windows 11 (24H2). Official release notes list the security fixes and quality improvements included in the package, and the public KB entry initially did not list any storage-device regressions as a known issue. Within days of that rollout, however, two distinct problems surfaced in parallel: enterprise deployment failures when distributing the update via WSUS/SCCM, and scattered—but technically consistent—reports that certain storage devices become inaccessible under heavy sequential write workloads after the update.
The enterprise insted error 0x80240069 and prompted Microsoft to apply a Known Issue Rollback (KIR) and re-release a corrected package for managed deployment channels. This separate failure mode is a reminder that staged delivery and enterprise distribution paths exercise different code paths than consumer Windows Update.
The storage reports emerged from enthusiands-on testers who independently reproduced a nearly identical symptom profile: during a sustained, large write operation (community tests commonly cite a threshold near 50 GB), the target NVMe drive stops responding and disappears from Windows. SMART/controller telemetry becomes unreadable to host utilities, and files written during the failure window may be incomplete, corrupted, or otherwise unrecoverable. In many reproducible cases a reboot reinitializes the controller and temporarily restores visibility, but the same workload often reproduces the failure.

What the reports show — symptoms, triggers, and affected hardware​

The symptom fingerprint​

• Drive disappears from File Explorer, Device Manager, and Disk Management mid-write.
• SMART and controller telemetry appear unreadable to diagnostic utilities.
• Reboot can mporarily; a minority of reports show devices remaining inaccessible after resting vendor intervention.
• Files or partitions written during the event window may be corrupted or missing.

These behaviors are consistent with a controller sh, or host/driver timing fault that makes the device effectively offline even though present on the bus.

The typical trigger​

Community reproductions converge on sustained sequential writes as the most reliable trigger. Multiple testers reported failures after roughly 50 GB or more of continuous writes and observed controller utilization spikes (reports note controller load around or above 60%) at the time of failure. Typical real-world triggers include large game downloads/updates, mass file copies, archive extraction, cloning, or media exports—activities common to gamers and content creators.

Which SSDs are implicated​

Early, community‑compiled lists and hands‑on reproductions over-represent drives using certain Phison controller families and some DRAM‑less designs. Models that have appeared repeatedly in aggregated reports include, but are not limited to:

• Corsair Force MP600
• Phison PS5012‑E12 controller‑equipped SKUs
• Kioxia Exceria Plus G4
• Fikwot FN955 (community-named example)
• SanDisk Extreme PRO M.2 NVMe 3D SSD
• Adata SP580
• Kingston SNV2S2000GN

These model lists are community-sourced investigative leads rather than vendor-confirmed recalls; they are evolving as more hands-on tests accumulate. Several popular SSDs — for example the Samsung 990 Pro and WD Black SN7100 in community tests — have been reported as not showing the fault in the same reproductions, indicating the regression is neither universal nor limited strictly by brand.

Technical context: why a Windows update can cause storage regressions​

Modern NVMe SSDs are complex subsystems where controller firmware, DRAM or Host Memory Buffer (HMB), and the host OS storage stack interact tightly. Many DRAM‑less SSDs rely on the Host Memory Buffer to borrow a small portion of system RAM for caching mapping tables and metadata. When the host alters timing, memory allocation, or buffering behavior, it can expose latent firmware bugs or corner-case controller behavior that only manifest under sustained stress.
The symptom pattern reported here — a device becoming unresponsive mid-write with unreadable SMART — is consistent with either:

• a host-side kernel/driver regression that drives the controller into a bad state, or
• a firmware edge-case in specific controllers that becomes visible when the host applies a particular I/O or memory allocation profile introduced by the update.

Both possibilities are plausible and not mutually exclusive. Historically, similar incidents required coordination between Microsoft and SSD vendors to publish firmware updates or targeted mitigations (such as blocking upgrades until firmware is applied) while Microsoft adjusted host-side behavior.

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Timeline and verification status​

• Microsoft released KB5063878 on August 12, 2025 as a cumulative update for Windows 11 (24H2). The KB entry initially did not list storage-device failures as a known issue.
• Within 48–72 hours, community testers and several specialist outlets began publishing reproducible reports showing devices vanishing under sustained writes after installing the KB. Typical repros reported failures after ~50 GB written and controller utilization spikes. regators and enthusiast sites assembled model lists based on community reports; many implicated drives use Phison controller families, particularly some DRAM‑less configurations.
• Microsoft acknowledged and mitigated a separate WSUS/SCCM deployment regression (error 0x80240069) for the package; as of the earliest community reporting, Microsoft had not universally confirmed a storage-related known issue in the public KB. That gap means community observations remained hypotheses pending vendor telemetysis.

This timeline underscores an important point: community testing can identify reproducible fault patterns quickly, but formal remediation and definitive root‑cause attribution require coordinated telemetry and vendor-level confirmation.

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Practical guidance: what users and admins should do now​

The immediate priority for any reader using internal NVMe storage is data protection. The community consensus and practical mitigations are straightforward and conservative:

• Back up critical data immediately to an independent device or cloud service. Backups are the only guaranteed defense against drive‑level corruption.
• If KB5063878 is not yet installed and your workflow regularly involves large sequential writes (game installs/updates, cloning, video exports), consider delaying the update until vendors or Microsoft publish mitigation guidance.
• If the KB is already installed, avoid large, sustained writes (> ~50 GB) on at‑risk devices until you confirm vendor guidance or a Microsoft updaent tools (Corsair iCUE, SanDisk Dashboard, Kioxia Storage Utilities, or CrystalDiskInfo/smartctl) to monitor SMART and capture telemetry if anomalies appear.
• Check SSD vendor support pages for firmware updates. Vendors have histmware patches to address similar compatibility issues; apply those updates only after backing up the drive and following vendor instructions. Firmware flashing carries inherent risk and should be staged and tested.
• For enterprises: inventory endpoints for at‑risk models and pause deployment of KB5063878 on exposed fleets until vendor/Microsoft guidance is available. Use WSUS/SCCM or MDM controls to withhold the update and schedule heavy I/O tasks to systems not yet patched. Microsoft has previously used Known Issue Rollback and deployment controls to mitigate enterprise impact.

If a drive becomes unreadable during an event:

• Stop further writes and avoid repeated reboots that might overwrite volatile controller state. Capture logs and, if possible, a forensic image of the device for vendor support.
• Use vendor diagnostic tools to collect SMART and controller logs; these are crucial for vendor triage.
• Contact the SSD vendor’s support line with a reproduction recipe and logs; in many cases vendors have needed that telemetry to determine whether a firmware update is required.

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Analysis: strengths of the community response and strengths in Microsoft’s servicing model​

The rapid detection and reproduction of the issue by community testers is a positive demonstration of the enthusiast ecosystem’s value.oducible test scripts, workload parameters (the ~50 GB continuous write window), and device lists allowed mulirmations within hours, creating pressure for vendors and Microsoft to investigate. Those community signals often accelerate vendor triage and firmware rollouts in ways that formal f might not.
Microsoft’s servicing tools — notably Known Issue Rollback (KIR) and staged delivery — also provide mechanisms to limit exposure when problems appear in the field. The swift mitigation for the WSUS/SCCM installation regression in this KB demonstrates that those controls can reduce enterprise disruption while a permanent fix is prepared. Those same mechanisms would be the logical path to limit exposure should a confirmed storage‑level known issue be declared.

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Risks, gaps, and unresolved questions​

While the community evidence is strong and reproducible in many hands-on tests, several factors raise caution about drawing broad conclusions:

• Lack of consolidated vendor confirmation: At the time community reporting intensified, most SSD vendors had not published unified advisories explicitly tying KB5063878 to a permanent hardware fault for every model listed by enthusiasts. The absence of vendor verification creates a risk of over‑attribution or false positives in model inventories. This is a critical gap because vendor telemetry and firmware debug logs are necessaer the trigger lies in OS timing, controller firmware, or a combination.
• Sampling bias: The reports originate largely from enthusiast testers and heavy‑I/O workloads. Typical consumer use cases may never exercise the precise trigger window, making discovered incidence rates difficult to extrapolate to the entire installed base. The distributed nature of community reporting favors experienced testers who run large transfers and stress tests.
• Incomplete root-cause attribution: Two plausible loci exist — host-side kernel/driver changes or firmware-level edge cases. Both require coordinated telemetry to confirm. Until Microsoft or the SSD vendors publish a detailed root-cause disclosure, operational recommeonservative and focused on mitigation rather than definitive fixes.
• Potential for data loss escalation: Some community reports show drives that remained inaccessible after reboot or that had corrupted metadata. Those outcomes indicate the event is more than a transient performance hiccup; it is a real data‑integrity threat for users without backups.

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What vendold do (and what to expect)​

The technical resolution of an interaction like this typically involves a coordinated approach:

• Vendors should gather controller-level logs and reproductions, confirm whether specific firmware revisions are vulnerable, and publish firmware updates for affected models if needed. These updates should be accompanied by clear updatek warnings.
• Microsoft should monitor its telemetry for elevated device‑offline events tied to OS builds and, if confirmed, publish a Known Issues entry and either deploy a targeted mitigation or coordinate with vendors to apply upgrade blocks until firmware is installed. KIR and upgrcedent in similar incidents.
• Enterprises should expect guidance that allows them to triage and exclude at‑risk devices from broad KB deployment until vendor-validated firmware revisions and Microsoft mitigations are in place.

Transparent timelines, clear firmware version numbers, and automated vendor tools that can check and apply safe firmware revisions will reduce the risk and friction of remediation. Until then, administraative and treat this as a data‑integrity risk rather than merely a performance issue.

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Practical checklist for Windows gamers and enthusiasts​

• Back up: Copy critical saves, projects, and personal data to an external drive or cloud before performing large updates or installing KB5063878. Backups must be independent of the at‑risk internal SSD.
• Delay if possible: If you haven’t installed KB5063878 and you frequently perform large installs or updates, defer the update until vendor guidance is available. Use Windows Update “Pause updates” or en Monitor: If you installed the KB, avoid doing large sequential writes. Use vendor dashboard tools to check SMART and firmware versions and to capture logs if abnormalities occur.
• Firmware-first: Check your SSD manufacturer for firmware advisories. If a firmware update is provided, back up first and apply the firmware per vendor instructions. Test after updating.
• If a drive vanishes mid-write: Stop further writes; capture logs and images if the data is critical; contact vendor support and include a reproducible recipe and diagnostic output. Repeated reboots can compli.

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Final assessment​

The convergence of independent, reproducible community tests — showing drives disappearing after roughly 50 GB of sustained writes and implicating a cluster of Phison‑controller devices — constible signal that should be treated urgently by both users and vendors. The evidence so far is strong for a workload‑triggered regression that can expose firmware or host-side weaknesset‑cause attribution requires vendor telemetry and Microsoft validation before the community headline can be escalated to an official product recall or permanent designation.
For gamers andregularly move or install large files, the risk is consequential: file corruption and drive inaccessibility are not abstract performance problems, they are real data‑integrity risks. Until vendors and Microsoft publish coordinated mitigation steps — firmware updates, a Microsoft-known issue entry, or an upgrade block — the safest posture is conservative: back up, avoid sustained large writes on potentially affected drives, and apply only vendor‑recommended firmware updates after a verified backup.
The current situation highlights an uncomfortable but unavoidable truth in modern PC ecosystems: the tight coupling of OS behavior and device firmware means that even routine security rollups can surface hardware edge cases. Robust pre-release telemetry, vendor coordination, and clearer post‑release communications would reduce both the real risk and the whiplash effect when problems appear. For now, proactive backups and cautious patch management remain the most effective defenses against this class of failure.

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Source: PCGamesN Your gaming SSD could fail if you install this Windows 11 update, say reports