Windows 11 KB5063878 Update Not Linked to SSD Failures: What It Means

A cluster of community test benches and vendors dug into one of this summer’s more alarming update chases: after Microsoft’s August 12, 2025 cumulative for Windows 11 24H2 (KB5063878) some users reported NVMe drives disappearing mid‑write and, in a minority of cases, returning corrupted or unreadable — but the official industry response so far points to a more complicated, and possibly non‑software, explanation. Multiple outlets and vendors say Microsoft’s telemetry and Phison’s lab validation found no reproducible link between the update and mass drive failures, yet a new line of reporting from enthusiast groups claims an alternate root cause: pre‑release engineering firmware leaked into a subset of retail SSDs, which could be triggered into failure by the same heavy‑write patterns that brought the issue to light. The story is still unsettled; this feature pulls apart the evidence, verifies what vendors say they tested, flags claims that remain unverified, and outlines practical steps users and administrators should take now.

Background / Overview​

Shortly after Microsoft shipped KB5063878 (OS Build 26100.4946) on August 12, 2025, hobbyist test runs and social posts documented a consistent failure profile: sustained, large sequential writes — commonly around 50 GB or more and often on drives already >60% full — could produce an abrupt device disappearance from Windows (File Explorer, Device Manager and even BIOS in some reports) and in some cases unreadable SMART/controller telemetry. Several independent test benches reproduced the pattern and published model-level lists and test logs that accelerated media attention. (support.microsoft.com) (tomshardware.com)
Microsoft and storage partners investigated. Microsoft’s support bulletin and a subsequent service alert indicated that internal testing and telemetry had not revealed an increase in drive failures after the August update and that the company had not been able to reproduce the failure pattern on up‑to‑date systems. Microsoft said it would continue to monitor reports while collecting affected‑system telemetry. (support.microsoft.com) (bleepingcomputer.com)
Phison — whose controllers are used across many consumer NVMe SKUs and which was singled‑out repeatedly by community testing — publicly reported an extensive validation campaign. In its statement the company said it had run more than 2,200 test cycles totalling over 4,500 cumulative hours on drives that were reported as potentially impacted, and that it could not reproduce the reported failures; Phison also said it had received no verified partner or customer reports showing a systemic problem. Several independent technology outlets reported, summarized, and corroborated Phison’s testing announcement. (neowin.net, windowscentral.com)
That official line — Microsoft: “no connection found”; Phison: “unable to reproduce” — left open two important possibilities: either the root cause is rare and hardware/batch‑level (so telemetric sampling missed it), or the reported incidents were coincidental hardware failures amplified by confirmation bias. Community engineering teams, however, continued to press for an explainable trigger.

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The new claim: engineering firmware in the wild​

A late August report aggregated by Neowin relayed a claim from a China‑based PC DIY Facebook group (PCDIY!) and its admin, Rose Lee: that the drives which failed were running pre‑release engineering firmware — not final production firmware — and that those engineering (pre‑final) firmwares contained bugs that could be triggered by the Windows write workload after the update. According to the post summarised in reporting, Rose Lee said Phison engineers verified the anomaly in lab conditions. If true, this would explain why Phison’s publicly disclosed validation on production SKUs failed to reproduce the fault: vendors and Microsoft would reasonably have tested retail firmware builds, whereas a small subset of units that accidentally shipped with engineering firmware could behave differently. (neowin.net)
Why would engineering firmware exist on consumer drives? The PCDIY account argues that some builders or distributors purchase drives that were flashed using mass‑production tools before the vendor’s final firmware image was applied, or that leftover test/engineering builds made their way into retail boxes. The theory is plausible as a logistic failure mode — engineering builds sometimes circulate inside supply chains for validation — but the chain of custody claim (which SKUs, which batches, which distributors) remains unproven in public reporting. The PCDIY claim, as it currently stands, is a potentially plausible explanation that fills the contradiction between broad lab validation and narrow, repeatable community reproductions — but it is not independently verified by a vendor press release or Microsoft communication at this time. Reporters and vendors we reviewed have not published documentation tying specific retail serial‑number ranges to engineering firmware images. (neowin.net)
Caveat: the PCDIY assertion that Phison engineers validated the engineering‑firmware trigger in lab appears in secondary reporting (Neowin), but Phison’s official public update remains that it could not reproduce the reported issue in its broad validation program. That inconsistency matters: vendors typically won’t confirm internal lab reproductions publicly until they have a full forensic picture. Treat the PCDIY claim as an investigative lead, not a finished root‑cause verdict. (neowin.net)

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What the vendors actually tested (and what that means)​

• Phison: public statement of a rigorous internal validation campaign — 2,200+ test cycles and 4,500+ hours — unable to reproduce the failures reported on social media and by community labs. Phison also pushed guidance around thermal best practices for high‑performance drives and said it would continue to work with partners. Multiple tech outlets covered Phison’s announcement. (neowin.net, windowscentral.com)
• Microsoft: service bulletin and follow‑up said Redmond’s telemetry and internal test efforts did not show a spike in drive failures tied to KB5063878, and the company asked affected users to provide detailed reports (Feedback Hub or business support) so it could continue analysing. Microsoft’s KB page for KB5063878 initially listed no storage‑related known issues. (support.microsoft.com, bleepingcomputer.com)

What this combination shows: large‑scale vendor and platform telemetry did not surface an epidemic of failing drives correlated with the update roll‑out. That weakens any claim of a universal, update‑level bug. Nonetheless, telemetry and test farms are blunt instruments relative to the real world: a hardware batch or a rare pre‑production firmware image could create a small but real set of failures the telemetry doesn’t reveal.
Independent community benches did produce reproducible failures in narrow test conditions (single‑machine, particular motherboard/BIOS/firmware combinations and specific write patterns), and those tests are how the concern initially rose to prominence. Those reproductions remain important forensic evidence because they show a workload profile that triggers device disappearance in certain setups: sustained high‑volume sequential writes to moderately‑full drives. (tomshardware.com, windowscentral.com)

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Technical plausibility: how an OS change can surface firmware defects​

SSD controllers and the Windows storage stack are tightly coupled. Under normal conditions this relationship is robust, but narrow timing, buffer allocation, HMB negotiation (Host Memory Buffer), command queue depth, power‑management handoffs, or host‑issued flush semantics can exercise previously dormant firmware code paths. Several plausible mechanisms can explain why a host update might expose a firmware bug:

• Host memory or HMB negotiation changes increase controller memory pressure on DRAM‑less designs, exposing allocation race conditions. (This was the central mechanism in prior Windows/24H2 HMB incidents.) (support.microsoft.com)
• Changed I/O timing or larger write‑back windows under the updated host can trigger an unhandled corner case in pre‑release controller firmware, causing the controller to stall or lose mapping metadata.
• Thermal or SLC‑cache exhaustion under prolonged writes magnifies firmware latencies and GC pressure; if a controller’s firmware mishandles long GC cycles or command timeouts it can lock up and stop responding to the host. (datarecovery.com)

All of the above are established, credible failure modes in flash ecosystems; they do not require a software‑only root cause. That’s why a combination of careful vendor firmware logs, drive serial/batch auditing and host trace captures are needed to reach a firm root cause.

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Strengths and weaknesses of the current evidence​

Strengths​

• Independent test benches have consistently produced a reproducible trigger pattern (sustained large writes, ~50 GB+, often when drive >60% full). That reproducibility is meaningful; it provides a focused forensic remit for vendors. (windowscentral.com)
• Phison publicly disclosed an extensive internal testing program (2,200+ cycles / 4,500+ hours), which demonstrates the vendor took the reports seriously and attempted large‑scale validation. Multiple reputable outlets reported Phison’s numbers. (neowin.net, windowscentral.com)
• Microsoft has published its inability to find telemetry‑level evidence linking the KB to an elevated failure rate, and has requested customer reports for any remaining anomalies. That transparency, while not definitive proof, reduces the likelihood of a broad platform‑level regression. (support.microsoft.com)

Weaknesses and risks​

• The PCDIY claim that pre‑release engineering firmware explains the discrepancy between community reproductions and vendor tests is currently unverified by an official vendor disclosure. Neowin relayed the PCDIY account, but there is no public Phison press release that confirms which, if any, retail serial‑number ranges shipped with engineering firmware. Treat that explanation as an investigative hypothesis, not a confirmed root cause. (neowin.net)
• Community reproductions often used a single test machine, single motherboard/BIOS, or other constrained variables; reproductions are compelling but may not generalize across all system topologies. This complicates definitive public pronouncements.
• A small number of irrecoverable failures (e.g., one WD SA510 unit reported by a tester) raises the specter of bad batches or counterfeit/altered product entering channels — a distribution risk that only vendor serial audits and RMAs can resolve. (windowscentral.com)

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Practical guidance: what owners, builders and admins should do now​

The situation remains fluid. Follow these prioritized steps to minimize risk and preserve diagnostics.
1.) Back up immediately and frequently. If you’ve installed KB5063878 and store critical data on at‑risk drives, take a full image and an off‑device copy before running large transfers. Imaging preserves forensic data for vendor diagnosis.
2.) Avoid sustained large sequential writes (>~50 GB) to drives that are more than ~60% full until you confirm your firmware and vendor guidance. Break large operations into smaller batches. (windowslatest.com)
3.) Check vendor support portals (Corsair, WD, Kingston, SanDisk, etc.) for firmware updates and advisories; apply firmware only after backing up data and following the vendor’s recommended procedure. Firmware patches are the canonical remediation for controller bugs. (neowin.net)
4.) If you experience a disappearing drive:

• Power down the system and preserve the drive powered‑off for vendor support if data recovery is needed.
• Do not reformat or run destructive operations before speaking to vendor support; capture logs, collect system Event Viewer entries and capture the machine state if possible.
• If you must attempt recovery, image the drive first (write‑blocker recommended) and then attempt vendor tools. If you lack expertise, consult a professional recovery provider. (datarecovery.com)
  5.) In the case of performance slowdowns after heavy writes: SSD behaviour where write speed collapses after SLC cache exhaustion is a known phenomenon on many designs. Vendors sometimes recommend a Secure Erase or a firmware update to restore baseline performance — but Secure Erase is not a universal cure and should be performed only following vendor guidance and after backup. (Note: Secure Erase may reset SLC partitioning and mapping state, but it is also an operation that should be used with caution.) If a vendor has published Secure Erase as a fix for a specific SKU, follow that official guidance. (superuser.com, forums.tomshardware.com)
  6.) For fleet administrators: stage KB5063878 in a test ring that mirrors your storage hardware; run your organization’s largest write workloads before broad deployment and validate vendor firmware levels first. If you run image‑based provisioning, verify that images are hardened with the vendor‑recommended SSD firmware.

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Interpretation and risk assessment​

• The most likely broad conclusion, based on vendor telemetry and public statements, is that KB5063878 did not introduce a widespread, reproducible defect that bricks consumer SSDs in the field. Microsoft’s telemetry and Phison’s extensive validation both point away from a universal platform regression. (support.microsoft.com, neowin.net)
• However, the reproducible community failures and the PCDIY hypothesis remain meaningful signals that cannot be dismissed as pure noise. If even a small number of retail units shipped with engineering firmware, they could fail under narrowly defined host workloads — producing high impact for those owners even as telemetry on millions of devices remains clean. That gap between “rare but real” and “systemic” is why cautious, targeted mitigations and serial‑level forensics are necessary. (neowin.net, windowscentral.com)
• The worst‑case scenario for users (irrecoverable data loss) is low probability but non‑zero given the documented NG Level 2 outcomes from community testing. That justifies the conservative advice from independent labs and vendors: back up, avoid heavy writes on patched systems until you have applied vendor firmware, and escalate any device failure promptly to vendor support with logs and images for forensic review. (windowscentral.com)

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What remains to be done (and what to watch for)​

• Public vendor confirmation of the PCDIY claim (if real) would require Phison or SSD brands to publish a traceable serial/batch advisory saying certain assemblies inadvertently shipped with engineering firmware. That would be a strong smoking gun; at present no vendor has made such a public admission. Seek vendor RMA guidance and serial‑range advisories in the coming days. (neowin.net)
• Independent labs and vendors should (and likely will) publish coordinated reproduction logs that include host‑side traces (ETW, kernel logs), NVMe command captures and drive microcode logs. Those artifacts are the route to a definitive cause. Watch for forensic write‑ups from specialist outlets; they typically appear after vendors supply firmware revisions and/or sample‑level confirmations.
• Administrators responsible for large fleets should wait for a coordinated advisory before mass‑deploying KB5063878, and treat vendor firmware updates as the primary remediation path rather than registry workarounds unless vendor literature explicitly recommends otherwise. (support.microsoft.com)

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Final assessment​

The public record today supports two simultaneous truths: (1) community test benches reproduced a narrow, repeatable failure mode that occurs under high sustained writes on certain drives and (2) platform and controller vendors’ large‑scale telemetry and lab validation have not identified a reproducible, update‑driven failure affecting production firmware at scale. The PCDIY claim — that a small set of drives running pre‑release engineering firmware were the actual victims and that those units were triggered by the Windows workload — is plausible and would elegantly reconcile the discrepancy, but it remains an unverified investigative lead until vendors publish confirmatory forensic evidence.
For now, users should act conservatively: back up, avoid large sequential writes on patched systems with suspect drives, check vendor tools for firmware updates, and preserve failed drives for vendor diagnostics rather than immediately reformatting. That pragmatic, data‑preserving posture protects the small number of users who may be affected while allowing Microsoft, Phison and drive manufacturers to finish the forensic work necessary to close this chapter with a definitive, auditable root cause. (support.microsoft.com, neowin.net)

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Source: Neowin Root cause for why Windows 11 is breaking or corrupting SSDs may have been found

The investigation into a wave of disappearing and allegedly “bricked” NVMe SSDs that followed Microsoft’s August Windows 11 security rollup has taken a new turn: community researchers now say the problem was triggered not by Microsoft’s patch but by pre-release engineering firmware present on a small subset of drives — a claim that, if true, reframes the incident from an operating‑system bug to a supply‑chain and firmware management failure.
The new narrative is straightforward: several community testers traced the failures to drives running non‑production firmware builds, and those builds behaved incorrectly when exposed to the combination of heavy sequential writes and the updated Windows I/O behavior introduced in August. The largest SSD controller vendor implicated by users, Phison, performed extensive lab testing — totaling thousands of hours and thousands of cycles — and reported it could not reproduce a wide‑scale failure tied to the Windows update. Microsoft likewise reported no telemetry‑based link between its August 12, 2025 cumulative update and the reported storage failures. The result is a messy, multi‑vector incident that highlights how firmware, hardware, and OS changes can intersect in real‑world systems and how hard it can be to reach a definitive conclusion from scattered user reports.

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Background​

What happened, in brief​

In mid‑August, a handful of users reported NVMe SSDs vanishing from Windows during or after large file transfers. Symptoms ranged from temporary disappearance (drive absent from Device Manager and File Explorer until a reboot) to persistent loss, RAW partitions, unreadable SMART, and data corruption. Initial signal analysis suggested the failure fingerprint often involved:

• sustained sequential writes (tens of gigabytes in a single operation),
• SSDs with high occupancy levels (commonly reported above ~50–60% used),
• drives built on certain controller families used widely in retail NVMe products.

Community test benches, single‑user reproductions, and social posts produced alarm and pointed fingers at an August Windows 11 24H2 security update (identified in some cases as KB5063878). That update was rolled out by Microsoft on August 12, 2025 and included a mix of security fixes and broader platform updates.

Who’s involved​

• Microsoft: released the August update and performed internal testing and telemetry analysis after reports surfaced.
• Phison: a major NAND controller vendor whose controller families power many consumer NVMe SSDs; it conducted a multi‑thousand‑hour internal test program after being alerted to the problem.
• Community groups: testers and hobbyist lab benches (including a named tech community group) published reproducible test results and hypotheses.
• SSD brands: downstream manufacturers that integrate Phison controllers into retail drives were part of the investigation and, in some cases, published firmware updates later in the lifecycle.

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The official responses and lab testing​

Phison’s lab program​

Phison responded with an extensive internal test program that ran well into the thousands of hours and multiple thousands of test cycles. The public statements from the company describe an inability to reproduce the drive disappearance in its lab testing and report no verified partner or customer complaints that matched the scale of online claims. Phison also suggested thermal stress could be a contributing factor in high‑workload scenarios and recommended the use of heatsinks or thermal pads as a precaution for heavy sustained throughput.
The most significant takeaway from Phison’s statement is the combination of scale and negative result: very large test coverage that did not reproduce the failure mode described on social channels. That kind of negative finding is valuable, but it does not rule out narrow edge cases or specific field configurations — particularly when firmware variants exist outside the mainstream production channel.

Microsoft’s conclusion​

Microsoft investigated the reports tied to the August cumulative update and found no evidence of a direct causal link between the update and the reported SSD failures. The company’s findings were based on telemetry, partner engagements, and internal repro efforts. Microsoft’s message was unequivocal in tone: the update is not responsible for a systemic spike in drive failures.
That said, Microsoft also acknowledged it would continue to monitor feedback and investigate specific user cases, especially when partners provided new data points. The broader corporate posture was to discourage immediate blame and to instead pursue methodical analysis.

What this means technically​

When both a silicon vendor and the OS vendor report no reproducible root cause, there are a few reasonable interpretations:

• the issue is real but rare, dependent on a combination of factors that labs did not replicate;
• the issue is caused by non‑standard firmware or out‑of‑band builds that aren’t represented in vendor test pools;
• user equipment or usage (e.g., power anomalies, thermal throttling, or hardware defects) is the proximate cause but was conflated with the update by timing.

The public replies from the big players are consistent with a scenario in which the update could provoke a failure only in very narrow conditions.

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The PCDIY claim: pre‑release engineering firmware as the root cause​

What the community found​

A prominent community group reported that at least some of the drives exhibiting the failure pattern were running pre‑release engineering firmware rather than the mass‑production firmware that normally ships to retail units. According to the group’s post, testing showed drives running engineering builds crashed under the tested Windows 24H2 write patterns, while those same models on confirmed production firmware did not.
The group’s administrator also said the issue had been confirmed by engineers in the SSD controller ecosystem, lending the claim some weight. If engineering firmware — which may contain debug hooks, unoptimized cache behavior, or unfinished queue handling — reached consumer devices, it could plausibly explain why a small subset of devices failed when the large majority did not.

Why this is plausible technically​

Firmware controls how an SSD handles host commands, manages DRAM or HMB (Host Memory Buffer), schedules garbage collection, and responds to thermal and power events. Engineering firmware builds are often used in R&D to iterate features quickly; they may intentionally expose diagnostic modes or skip hardening steps used in production images.
Possible vectors for engineering firmware reaching end users include:

• factory programming mistakes where the wrong image is flashed to a batch,
• distribution of developer/evaluation units into the retail channel,
• third‑party integrators or OEMs using pre‑release images during early builds and failing to update before shipment,
• refurbished or used devices exchanged in secondary markets with odd firmware histories.

Any of these paths could produce a small population of drives behaving differently from the mass‑market baseline.

Verification and caveats​

This pre‑release firmware hypothesis is compelling and consistent with the observed distribution (few affected units among many). However, it remains difficult to fully verify from public information alone. The claim relies on community testing and a social‑media post; independent confirmation directly from the controller vendor or the affected SSD manufacturers — such as publishing serial‑range diagnostics or reproducible lab results — was limited at the time of reporting.
In short: the engineering‑firmware hypothesis is a plausible explanation that explains both the rarity of failures and why vendor labs, testing largely production images, were unable to reproduce the issue. It is still a hypothesis and should be treated with cautious acceptance until vendors publish definitive forensic evidence.

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Deep dive: how OS updates, firmware, and heavy writes interact​

The I/O stack and failure fingerprints​

Modern NVMe SSDs are complex devices with multiple interacting layers:

• the host OS issues NVMe commands and manages caching policies (write‑back vs. write‑through),
• the SSD controller handles command queues, flash translation layers (FTL), wear leveling, garbage collection, and power management,
• firmware orchestrates DRAM usage (on DRAM‑equipped drives) or HMB usage on DRAM‑less drives, and implements error handling.

When a large, sustained write floods the device — for example, copying dozens of gigabytes or installing a 50+GB game — the SSD’s internal garbage collection and write buffering kick into high gear. If firmware mishandles queue management, misreports free space, or incorrectly sequences thermal throttling, that heavy operational stress can expose latent bugs. An OS update that subtly changes write aggregation or queue behavior could, in theory, surface a bug that previously went dormant.

Common weak points that lead to disappearance​

• HMB misconfiguration: DRAM‑less drives that rely on host memory can mismanage pointers or timeouts under certain drivers or host behavior.
• Queue depth and timings: firmware may assume certain timing windows; changed timings can provoke unexpected states.
• Thermal limits and throttling: extended writes raise temperatures; aggressive thermal management that forces resets without graceful shutdown can leave devices unresponsive.
• Garbage collection lockups: badly implemented GC can block host commands, making a device appear to vanish.

Engineering firmware can intentionally expose debug paths or omit production mitigations, increasing the chances of hitting these weak points.

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Practical guidance for users and system administrators​

Immediate actions for worried users​

• Back up critical data now. If a drive is showing instability, copy irreplaceable files to another medium immediately before attempting repairs or firmware updates.
• Avoid large sequential writes on any SSD that is more than ~50–60% full until the root cause is confirmed or the drive’s firmware is known to be current.
• Check firmware version using the SSD manufacturer’s utility or nvme‑cli (on Linux). Confirm that the installed firmware is the latest official production release for that model.
• If firmware is outdated, update using the manufacturer’s recommended tool — but only after backing up data. Firmware updates can carry risk; do not interrupt the update nor remove power during the process.
• Use cooling for sustained loads. Applying an M.2 heatsink or enabling motherboard M.2 cooling can reduce thermal stress during heavy transfers.

Safe firmware update procedure (recommended steps)​

• Identify the SSD model and current firmware version via manufacturer tools or Device Manager / nvme-cli.
• Visit the SSD maker’s official support page and locate the firmware download for that exact model and capacity.
• Read the firmware release notes carefully; note any precautions and the version history.
• Back up all important data to a separate drive or cloud storage.
• Ensure a stable power environment (UPS recommended for desktops, high battery for laptops).
• Run the vendor tool and follow instructions to flash the firmware; do not interrupt the process.
• Reboot and verify the firmware version and SMART health after the update.

For IT departments and system builders​

• Treat firmware hygiene as part of build verification: check shipped units for production firmware before imaging or installation.
• Maintain a firmware inventory for SSDs used in fleets and schedule controlled updates during maintenance windows.
• Consider blocking or holding non‑essential OS updates until device firmware is validated on fleet hardware.

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Critical analysis: strengths, weaknesses, and risks​

Strengths of the community + vendor approach​

• Community reproducibility: independent labs and community testers produced reproducible failure patterns, which prompt vendor investigation — a model of crowdsourced triage.
• Vendor testing rigor: large‑scale lab tests (thousands of hours and cycles) provide meaningful negative evidence and help rule out systemic flaws in production firmware.
• Rapid mitigation options: firmware updates and safe‑guard blocks from OS vendors can contain exposure while investigations continue.

Weaknesses and open risks​

• Lack of transparency about exactly which firmware images and serial‑ranges were tested leaves room for doubt. Vendor statements that “we couldn’t reproduce” are valuable but not definitive for rare edge cases.
• The possibility that engineering or pre‑production images leaked into the retail supply chain is troubling; it suggests process control failures at manufacturing or distribution stages.
• Users in secondary markets (used/refurbished drives) may carry firmware histories unknown to buyers, enlarging the potential affected population and complicating forensic analysis.
• A non‑reproducible but real field failure has outsized reputational damage; vendors must balance full disclosure with legal and PR risks.

Systemic and supply‑chain implications​

If pre‑release images did reach consumer units, responsible parties need to find the leak point: factory flasher misconfiguration, mislabeled QA units, or distribution of evaluation samples. This event underscores the need for:

• stricter firmware traceability and serial‑range management,
• signed and validated production firmware chains,
• improved tooling in factories to prevent accidental flashing of engineering images.

Manufacturers and contract manufacturers must re‑examine stamping, imager tooling, and final QA checks.

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What to watch next​

• Public forensic dumps or coordinated vendor disclosures that map which firmware images were found on failing drives and whether those correspond to the engineering builds claimed by community testers.
• Manufacturer firmware‑release notes and targeted updates that explicitly address the failure fingerprint (e.g., fixes to HMB handling or queue management under heavy sequential writes).
• Microsoft or partner telemetry updates that either continue to find no link or that identify a tiny but valid correlation with specific firmware revisions or serial ranges.

Until those final pieces are shared, the safest posture for users is conservative: update firmware from official manufacturers, back up data, and avoid sustained large writes on near‑full drives.

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Conclusion​

The SSD disappearance saga that began in the wake of a Windows 11 August update is a textbook example of modern, complex failure modes where software, firmware, hardware, and distribution channels collide. The latest and most plausible explanation — that a small number of drives shipped with pre‑release engineering firmware — resolves some contradictions in the public record: it explains why vendor labs (testing production images) could not reproduce the issue while a handful of field cases nevertheless experienced catastrophic failures.
That explanation, however, is still a hypothesis until vendors publish matched, auditable forensic evidence. The incident exposes a painful truth for the PC ecosystem: even a tiny population of non‑production firmware units can create outsized fear and confusion when an OS update changes system behavior at scale. It also highlights the continuing importance of firmware hygiene: vendors must ensure production images are traceable and that factory and distribution tooling cannot accidentally ship engineering images to customers.
For end users, the immediate priorities are clear and pragmatic: back up data, verify and update SSD firmware only via official vendor tools, and avoid risky operations on drives that are heavily filled or showing early signs of instability. For vendors and OEMs, this episode should prompt a tightened focus on firmware traceability, stronger production‑image safeguards, and improved customer communication when community testers surface credible anomalies.
In the intersection of community research, vendor labs, and OS telemetry, speed matters but so does rigour. The evolving picture here suggests a misstep outside Microsoft’s update itself — but it is also a reminder that the chain of custody for firmware and the transparency of lab findings are as important as patching cadence in maintaining user trust.

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Source: Tom's Hardware New report blames Phison's pre-release firmware for SSD failures — not Microsoft’s August patch for Windows

A cluster of community test benches and vendor statements now point to a supply‑chain firmware issue — not a Windows code regression — as the most plausible explanation for the mid‑August reports of NVMe drives “vanishing” during large sequential writes after the Windows 11 August cumulative update (commonly tracked as KB5063878). Independent reproductions showed a repeatable failure window under sustained writes of roughly 50 GB on drives already substantially used, Phison’s lab program ran thousands of hours without reproducing a systemic fault in production images, and a community group identified pre‑release engineering firmware on a subset of affected units that reportedly fails under the same workload patterns — a finding that reconciles the apparent contradiction between community reproducibility and vendor/Microsoft negative results. (bleepingcomputer.com, tomshardware.com)

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Background / Overview​

In mid‑August 2025 Microsoft shipped the monthly cumulative/security rollup for Windows 11 24H2 (widely tracked as KB5063878, OS Build 26100.4946). Within days, hobbyist labs and independent testers published reproducible tests that triggered a specific storage failure fingerprint: during sustained, sequential writes (commonly reproduced at or near ~50 GB), some NVMe SSDs became unresponsive, disappeared from File Explorer/Device Manager/Disk Management, and in some cases returned corrupted or RAW partitions after a reboot. The pattern tended to surface more often on drives that were already partially full (community reports often cited >50–60% used capacity). (tomshardware.com, pureinfotech.com)
That reproducibility made the issue notable: it was not a purely anecdotal “one‑off” but a narrow, workload‑dependent phenomenon that independent benches could replicate. At the same time, large‑scale telemetry and vendor lab campaigns initially reported no correlated spike in drive failures across retail populations. Those two facts — reproducible community tests versus negative vendor reproducibility — set the stage for deeper forensic work. (bleepingcomputer.com, pureinfotech.com)

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Timeline: what happened and when​

• August 12, 2025 — Microsoft published KB5063878 as part of Patch Tuesday servicing for Windows 11 24H2. (pureinfotech.com)
• Mid‑August 2025 — Community researchers and independent test benches began publishing repeatable failure recipes: sustained, large sequential writes (≈50 GB+) to drives that are ~50–60% full trigger disappearance. Multiple posts, videos, and collations amplified the signal. (tomshardware.com, windowslatest.com)
• August 18–late August 2025 — Phison (a major NAND controller supplier) publicly acknowledged industry‑wide reports and launched an extensive lab program; Microsoft opened an investigation and asked affected users to provide diagnostics while its telemetry teams analyzed outcomes. (tomshardware.com, bleepingcomputer.com)
• Late August / early September 2025 — Phison reported large internal test campaigns (thousands of hours and test cycles) that did not reproduce a systemic failure in production firmware; Microsoft reported no telemetry‑based link between the update and a spike in drive failures. Community groups continued to report isolated cases. (tomshardware.com, bleepingcomputer.com)
• Early September 2025 — A prominent DIY PC community group (PCDIY) published a post claiming the affected drives were running pre‑release engineering firmware rather than final production images; the group said Phison engineers validated this finding in lab checks and that retail‑shipped drives with production firmware were not affected. This explanation, if borne out, reconciles why vendor labs that test production images saw nothing while community benches found repeatable failures.

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Who said what: the official and community positions​

Microsoft​

Microsoft investigated reports tied to KB5063878, attempting to reproduce the failure across its test fleets and telemetry. The company’s public posture — reflected in service alerts and communications to partners — concluded that it had not found a causal connection between the August security update and the types of hard‑drive failures circulating on social channels; Microsoft indicated it would continue to monitor feedback and engage partners for targeted reproducibility evidence. This was a time‑bound conclusion based on available telemetry and reproduction attempts at the time of the statement. (bleepingcomputer.com, windowslatest.com)

Phison​

Phison publicly acknowledged that it had been made aware of “industry‑wide effects” and launched a substantial internal validation program. In its public communications the company reported that thousands of cumulative test hours and multiple thousands of test cycles failed to reproduce a widespread problem in production firmware images. Phison recommended standard precautions (for example thermal mitigation) while continuing partner engagement and diagnostics. (tomshardware.com, bleepingcomputer.com)

Community test benches and hobbyist groups​

Independent testers produced the clearest, reproducible recipe: sustained sequential writes of roughly 50 GB on drives already significantly occupied tended to produce the failure mode. These reproducible results, published with logs and step‑by‑step instructions by credible hobbyist labs, compelled vendor engagement. A community group administered by Rose Lee (PCDIY) later reported that the drives failing in these benches were using engineering (pre‑release) firmware, a build type sometimes used in evaluation/dev units; that the engineering firmware misbehaved under the updated Windows I/O pattern; and that Phison engineers had verified the discrepancy between engineering and production firmware in lab checks. (tomshardware.com, windowslatest.com)

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Why engineering firmware explains the divergence​

The short technical argument is straightforward: modern NVMe SSDs are embedded systems with tightly coupled host/firmware interactions. Small host‑side timing or buffering changes can expose latent firmware race conditions — particularly in DRAM‑less designs that rely on Host Memory Buffer (HMB) or in firmware builds that have diagnostic hooks or unfinished corner‑case handling.

• Engineering or pre‑release firmware builds are typically used for development, validation, or early evaluation units. They may contain diagnostic code paths, un‑hardened state machines, or different cache management behavior that are not present in final production images. If such builds are flashed into devices that reach testing pools or retail channels, they can manifest behaviors that are invisible in production‑firmware test matrices.
• The observed failure fingerprint — a controller hang or loss of telemetry mid‑write, unreadable SMART, and device invisibility — is consistent with firmware state corruption or a controller deadlock rather than a purely host‑level filesystem bug. That is because firmware hang scenarios often leave the device unreachable to vendor utilities and the OS until the controller resets or a power‑cycle clears the stuck state. (tomshardware.com)

In this case, community reproductions exposed a workload (long sequential writes with a near‑full drive) that stresses SLC cache exhaustion, mapping table churn, and metadata updates — areas where unfinished engineering firmware may not have finalized resilience behavior. If the engineering image contained a subtle timing assumption that the OS change violated, it could trigger a controller hang on those specific units while leaving production‑image units unaffected — exactly the observed distribution.

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What has been verified and what remains unproven​

What is supported by independent evidence:

• The failure fingerprint — device disappearance under sustained writes with a common workload profile — was reproduced by multiple independent benches. (tomshardware.com, pureinfotech.com)
• Phison conducted an extensive testing campaign (thousands of hours / thousands of cycles) and publicly reported being unable to reproduce a systemic failure in their production images. (tomshardware.com, bleepingcomputer.com)

What is plausible but not fully proven in public:

• The claim that engineering firmware is the root cause is plausible, technically coherent, and was advanced by community researchers and a DIY group; that group reported Phison lab confirmation. However, at the time of these reports, a broad, independently verifiable vendor disclosure demonstrating sample‑level forensic logs or serial‑range mapping of affected units to engineering builds was limited or not widely published. Until vendors publish coordinated forensic artifacts (microcode logs, NVMe command traces, or serial‑range confirmations), the engineering‑firmware hypothesis should be treated as a strong investigative lead — not a finalized, vendor‑audited post‑mortem.

Because both Microsoft and Phison reported no broad production‑image failure, engineering firmware reaching end devices remains the most elegant reconciliation of the divergence between community reproducibility and vendor negative results — but it requires vendor confirmation to be elevated from likely to definitive.

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Practical impact and immediate guidance for Windows users and system builders​

This episode illustrates a simple practical truth: updates can change low‑level host behavior in ways that interact with firmware edge cases. Until a full vendor audit and public post‑mortem is published, the defensible playbook for users is conservative and focused on data safety.
Key immediate recommendations:

• Back up now. The single best mitigation against any update‑exposed storage regression is a verified backup to a separate device or cloud service. Do this before attempting firmware changes or recovery.
• Avoid large, sustained sequential writes on systems that have installed KB5063878 (or the related preview patch) until your SSD vendor confirms compatibility or releases firmware updates. Examples of risky activities: large game installs, archive extraction, cloning, and mass backup operations that write tens of gigabytes in a single run. (tomshardware.com)
• Inventory your SSDs and check firmware versions using vendor utilities. If your drive shows evidence of an older or unusual firmware string, follow vendor guidance. If your drive came from a secondary source (used/refurbished) or an obscure channel, pay particular attention to firmware provenance.

A concise, safe sequence for remediation and verification:

• Back up any irreplaceable data to an external device or cloud target.
• Use the SSD vendor’s official tool to query the drive’s firmware version and serial. Document these details.
• Check the vendor’s support pages for a published firmware advisory tied to the August 2025 timeframe; if a firmware update exists, read the release notes and follow the vendor’s recommended installation path.
• If you choose to update firmware, perform the update only after verifying backups and using the official utility; do not interrupt the update process.
• If a drive has already disappeared mid‑write, stop writing to the host, capture Event Viewer logs and vendor diagnostics if possible, and preserve the device for vendor RMA/forensics rather than immediately reformatting.

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For system builders and enterprises: staging and test ring best practices​

This incident is a reminder that enterprise rollout discipline and representative test rings are non‑negotiable for critical systems.

• Maintain a representative pilot ring that includes realistic workloads (including sustained write stress tests) and the same variety of storage devices found in production images.
• Delay broad deployment of a cumulative OS update until pilot passes include storage stress scenarios and vendor firmware matrix checks.
• Implement rollback playbooks that include restoring from backup images and vendor remediation steps — not only uninstalling the OS update.
• Consider a check of drive firmware inventory as part of patch validation for critical systems, particularly for devices purchased through non‑standard channels.

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Broader lessons for the industry​

Several structural lessons emerge from this episode:

• Co‑testing across vendors and platform owners must be deeper and more representative. Shared test harnesses that exercise host/firmware interactions under realistic stress workloads would catch narrow timing or HMB issues earlier.
• Supply‑chain provenance matters. Engineering or pre‑release firmware should not be allowed into retail supply chains; better factory flashing controls and serial‑range tracking could prevent leaks of evaluation images into production devices.
• Communications must be timely and clear. When community reproducibility collides with negative vendor telemetry, coordinated disclosure of sample‑level forensics (without compromising IP) helps users and administrators make data‑informed mitigation choices.

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What to watch next (and what would prove the hypothesis)​

The engineering‑firmware hypothesis is testable if vendors publish coordinated forensic evidence. Conclusive confirmation would include:

• Published vendor advisories that map affected serial ranges to specific non‑production firmware images.
• Forensic artifacts (NVMe command traces and controller microcode logs) demonstrating a distinct state transition or hang in an engineering image that does not occur in production images under identical host workloads.
• A coordinated vendor patch history that shows remediation targeted at firmware behaviors present only in pre‑release images.

Absent such disclosure, the hypothesis remains the most plausible reconciliation of the available evidence: reproducible community tests, large vendor negative reproducibility in production images, and a credible community claim backed by lab checks. Treat the finding accordingly: plausible and actionable, but not yet an audited final report.

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Strengths and risks: critical analysis​

Strengths of the current explanation

• Parsimony: the engineering‑firmware hypothesis elegantly explains why small, reproducible failure recipes emerged in the community while vendor labs — which predominantly validate production firmware — observed no systemic issue.
• Technical coherence: the failure fingerprint (controller hang, unreadable SMART, device invisibility) is consistent with firmware state corruption or deadlocks, which are plausible in pre‑release images that haven’t been hardened. (tomshardware.com)

Risks and open questions

• Limited public vendor confirmation: while community groups reported Phison verification, a fully auditable vendor disclosure (serial ranges, microcode logs) was limited in public channels at the time of reporting. Without that, attribution remains provisional.
• Recovery complexity: some users reported persistent device inaccessibility or truncated data. For those users, the cost of recovery is real and can be expensive. The incident underscores that even rare edge cases require robust backup discipline.

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Bottom line and user checklist​

The most defensible summary today is this: community labs reproducibly demonstrated a narrow workload that caused NVMe drives to disappear during large writes after the August 2025 Windows 11 cumulative update; vendor labs focused on production firmware reported no systemic failure; a credible community claim traces affected units to pre‑release engineering firmware that behaves incorrectly under the same workload, which would reconcile the mismatch if fully confirmed by vendor forensics. Until vendors publish coordinated, sample‑level evidence, treat the engineering‑firmware explanation as a high‑confidence investigative lead — actionable for users and admins, but not yet the final, audited post‑mortem.
Immediate checklist (one page):

• Back up important data now.
• Avoid large sequential writes on systems with KB5063878 installed until your SSD vendor confirms compatibility.
• Use vendor utilities to check and, if provided, apply official firmware updates (after backups).
• Preserve any failed drives and capture diagnostics for vendor RMA/forensics instead of reformatting.
• For enterprises: hold the update in pilot rings, run storage stress tests, and vet firmware inventories before broad deployment.

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The incident is a practical reminder that modern storage reliability is a cross‑discipline problem: OS updates, NVMe driver changes, controller firmware, manufacturing processes, and supply‑chain controls all interact. For now, the combination of community reproducibility and the engineering‑firmware hypothesis provides a coherent explanation that both preserves vendor laboratory credibility and points to an actionable remediation path: verify firmware provenance and update production images via official vendor channels while maintaining rigorous backups and staged update rollouts.

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Source: Lowyat.NET Engineering Firmware Identified As Root Cause For Windows 11 SSD Failures

Phison’s latest public testing and fresh community forensics have changed the tone of an urgent story that began as “Windows 11 is killing SSDs” and quickly morphed into a complex investigation at the intersection of OS updates, controller firmware, and supply‑chain quirks — with no single party yet owning every answer. What began as reproducible user reports of NVMe drives vanishing during large writes has been met by large‑scale vendor testing that could not reproduce a systemic failure, even as independent researchers point to a narrower, plausible explanation involving pre‑release or engineering firmware on a small subset of drives. The result is a case study in how modern storage ecosystems fail (and how they don’t), and it should prompt urgent, practical changes in update staging, firmware handling, and forensic transparency across the PC industry. (bleepingcomputer.com)

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Background / Overview​

In mid‑August, a cumulative Windows 11 update (commonly tracked as KB5063878 for 24H2) coincided with multiple independent user reports describing a consistent failure fingerprint: during large, sustained sequential writes — typically on the order of tens of gigabytes — NVMe drives would stop responding, disappear from File Explorer and Device Manager, and in some cases return with corrupted or inaccessible data. Testers reproduced the problem under repeatable conditions (large continuous writes to drives that were moderately used), which quickly amplified concern across enthusiast forums and specialist outlets. (windowslatest.com)
Two competing investigative threads emerged almost immediately. The first framed the incident as an OS‑level regression introduced by the August Windows update that changed host I/O timing, buffer handling, or Host Memory Buffer (HMB) allocation behavior — thereby exposing latent bugs in some controller firmware. The second argued that the failures were not rooted in the public release firmware at all, but instead in a small population of drives running pre‑release/engineering firmware (non‑production microcode) that behaved incorrectly under the same workload. Neither claim has been proven conclusively to the entire ecosystem’s satisfaction.

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Timeline of key events​

• August 12 — Windows 11 cumulative release (KB5063878) is rolled out; users soon notice storage anomalies under heavy write workloads. (windowslatest.com)
• Within days — community test benches reproduce the problem repeatedly using large single‑file writes (~50 GB) on drives that were ~50–60% full. (windowslatest.com)
• Mid‑ to late‑August — Phison, one of the largest NVMe controller vendors referenced in user reports, launches a large internal test program and publicly reports that it could not reproduce the alleged failure in production firmware after thousands of cumulative test hours. (tomshardware.com)
• Late‑August — Microsoft posts a service update stating it found no telemetry‑level evidence linking the KB to increased disk failures, while continuing to collect user reports. (bleepingcomputer.com)
• Early September — independent researchers publish a plausible lead: a subset of affected drives were running pre‑production/engineering firmware that could behave differently when exposed to the updated Windows I/O patterns. That hypothesis remains unverified at scale.

This timeline underscores both the speed of community reproducibility and the deliberate, measured pace of vendor verification — a contrast at the heart of the story.

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Technical anatomy: why sustained writes expose edge cases​

Modern NVMe SSDs are tightly integrated systems: host OS, NVMe driver (StorNVMe), PCIe link layer, controller firmware (FTL), DRAM or HMB, and NAND flash media all interact. Several specific technical mechanisms make the observed failure fingerprint plausible:

• Sustained sequential writes and FTL pressure: Continuous large writes force the controller to allocate mapping table updates, garbage collection, and wear‑leveling work. On DRAM‑less designs that rely on HMB, the timing and availability of host memory are critical. Changes in host allocation or timing can expose race conditions. (pureinfotech.com)
• Host Memory Buffer (HMB) sensitivity: DRAM‑less SSDs use HMB to store metadata. If OS updates alter HMB allocation behavior (size, lifetime, or timing of mapping fetches), controller firmware that assumed different host behavior may mismanage mapping state under heavy writes.
• NVMe command ordering and timeouts: Kernel or driver changes can alter command ordering or flush semantics. Firmware that assumes certain ordering guarantees may enter error states if those assumptions are violated.
• Thermal and capacity effects: Drives operating at higher fill levels (>50–60%) suffer greater write amplification and produce higher temperatures during long sustained transfers. Thermal throttling or RTOS resource starvation inside the controller can amplify latent bugs. Vendors recommended proper cooling as a mitigation while investigations continued. (tomshardware.com)

These mechanisms are not theoretical; they match the reproducible workload profile reported by multiple independent labs. The reproducibility — sustained writes of roughly 50 GB on partially filled drives — gives the event technical plausibility without proving an OS‑level root cause on its own. (windowslatest.com)

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What Phison tested and what they reported​

Phison publicly described an extensive lab verification program: more than 4,500 cumulative testing hours and over 2,200 test cycles across the drives flagged in community reports. After this work, Phison stated it could not reproduce the widespread failure, and that no partners or customers had reported corroborating incidents at scale. The company also called out a forged internal advisory that had circulated in enthusiast channels and recommended heatsinks for sustained‑workload deployments as a precautionary measure. (tomshardware.com, neowin.net)
Two technical points emerge from Phison’s statement:

• The vendor invested significant lab time and structured test cycles meant to replicate the community workload. A negative result at this scale suggests the failure is conditional — either tied to a narrow firmware revision, a specific system configuration, or non‑production firmware. (tomshardware.com)
• Phison’s recommendation for thermal controls is prudent; even when a root cause is not proven, reducing thermal and FTL stress reduces the chance that latent firmware bugs will surface. (tomshardware.com)

Cross‑checking independent reporting confirms Phison’s numbers and public position — multiple outlets quoted the same testing totals and conclusion, which strengthens confidence in the company’s public claim while not eliminating the possibility of rare, un‑reproduced field cases. (pcgamer.com, wccftech.com)

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Microsoft’s stance and telemetry findings​

Microsoft’s response followed standard enterprise practice: reproduce internally, examine telemetry, and invite affected customers to submit diagnostic traces. After internal verification and partner collaboration, Microsoft updated a service notice indicating it found no connection between the August security release and the reported drive failures based on telemetry and internal testing. The company continues to collect additional reports through standard support channels. (bleepingcomputer.com)
Important caveats in Microsoft’s position:

• A negative telemetry signal at the platform level does not prove every field case is unrelated — it only shows there is no measurable spike in failures corresponding to the update across monitored customers. Rare, hardware‑specific failures can evade early telemetry.
• Microsoft’s inability to reproduce the issue broadly aligns with Phison’s findings, which together shift the probability from "wide‑scale host regression" to "rare, conditional, or device‑specific interaction." Nevertheless, neither company published a definitive root‑cause post‑mortem at the time of the latest public statements. (bleepingcomputer.com, tomshardware.com)

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The “pre‑release firmware” hypothesis: plausible but unproven​

A key investigative thread advanced by community researchers argues that a small number of drives were shipped with pre‑release or engineering firmware that was not intended for wide distribution, and that those non‑production microcode images behaved incorrectly when exposed to the combination of sustained writes and Windows’ updated I/O patterns. This hypothesis helps reconcile three difficult facts:

• Community testers could reproduce a consistent failure profile on some drives.
• Phison and Microsoft’s large‑scale testing could not reproduce failures in production environments. (tomshardware.com, bleepingcomputer.com)
• A small, targeted firmware population could cause localized field failures that evade vendor telemetry and broad lab reproductions.

That said, the pre‑release firmware theory remains unverified in public. Vendors have not published a forensic trail proving that the failing units ran engineering firmware, nor have they supplied the NVMe command traces, microcode logs, or device‑level dumps that would conclusively prove the claim. Until such artifacts are provided and validated by independent labs, the pre‑release firmware explanation must be treated as a plausible investigative lead — not a concluded fact. Exercise caution before assuming this absolves any party.

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Strengths and limitations of the public evidence​

Strengths

• Multiple independent reproductions produced the same operational fingerprint (sustained sequential writes causing device disappearance), which is a rigorous signal compared with scattered anecdote.
• Vendor engagement (Phison, Microsoft, SSD manufacturers) and public lab testing increased transparency and reduced panic by offering structured testing results. (tomshardware.com, bleepingcomputer.com)
• The hypothesis space (FTL/HMB/thermal/timing) is technically realistic and consistent with prior edge cases in NVMe/DRAM‑less SSDs.

Limitations and unresolved questions

• No publicly released, vendor‑authenticated forensic capture (NVMe command traces + controller microcode logs + host kernel ETW traces) has yet tied the failure deterministically to a single root cause. That kind of evidence is required to move from plausible to proven.
• Public telemetry and lab testing are negative for a systemic failure, but they cannot exclude extremely rare or serial‑range‑specific manufacturing slips (e.g., pre‑release firmware images) without supply‑chain audits.
• The circulation of a forged internal advisory early in the incident undermined public trust and complicated triage by mixing verified test data with false claims.

Because the impact (data corruption, inaccessible drives) is severe even if probability is low, conservative operational responses are warranted while root causes are finalized.

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

• Back up immediately. Prioritize offline or cloud backups of critical data. This is the single most important step.
• Avoid large single‑run writes on suspect systems. Postpone mass game installs, disk cloning, or large archive extractions on systems using drives that match community‑reported models until the vendor advises otherwise. The reproducible workload was commonly a continuous write of ~50 GB on drives ~50–60% full. (windowslatest.com)
• Check vendor utilities and firmware versions, but follow vendor guidance. Use manufacturer tools to inventory firmware and apply only vendor‑published updates — do not apply unofficial flashes or rollback firmware unless explicitly recommended.
• Preserve failed devices for diagnostics. If a drive fails, avoid reformatting or destructive recovery attempts before contacting vendor support and capturing logs — these artifacts can be essential to a forensic resolution.
• Staged OS updates for fleets. Enterprises should push KB5063878 (or other updates) through pilot rings that include systems performing heavy write operations, and monitor for anomalies before broad deployment. Use WSUS/Intune to stage and control rollouts.
• Thermal mitigation for high‑load systems. Where practical, add heatsinks or improve airflow on NVMe drives used for sustained workloads — a simple precaution that reduces the chance that thermal stress will surface firmware corner cases. (tomshardware.com)

These steps balance caution with operational continuity and align with vendor advisories and community triage recommendations.

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Forensics and accountability: what needs to happen next​

A definitive resolution requires forensic artifacts and cross‑validation. Specifically:

• Vendors should publish anonymized, redacted traces that prove whether failing devices ran production or engineering firmware. Independent labs should validate those traces.
• A coordinated reproduction report showing NVMe command captures, host kernel traces (ETW), and controller microcode logs for both a failing unit and a non‑failing, same‑model unit would allow the community to isolate whether the observed behavior is firmware configuration‑specific or host‑induced.
• SSD manufacturers and controller vendors should adopt stricter QA to prevent pre‑release/engineering firmware images from escaping factory programming channels or distribution, if that proves to be the root cause.

Without these artifacts, public trust suffers and speculation fills the gap — a poor foundation for the next incident.

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Broader lessons for the Windows ecosystem​

• Co‑engineering fragility: The incident underscores the fragile interdependence between OS behavior and storage firmware. Small changes in host I/O semantics can surface latent controller bugs, especially in DRAM‑less/HMB designs. Rigorous cross‑vendor integration testing for widely distributed updates is crucial.
• Staged rollouts and telemetry escape hatches: Large updates should be staged with an explicit heavy‑I/O validation track. Telemetry should include targeted counters for unexpected device disappearance events to catch rare but high‑impact regressions early.
• Supply‑chain hygiene: The possibility that non‑production firmware could leave the factory or distribution channels (if verified) is an industry failure mode that deserves a formal supply‑chain QA response.

These policy and engineering takeaways will help prevent similar incidents from escalating in the future.

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Final assessment and risk outlook​

At present, the most supportable conclusions are:

• Community testers reproduced a narrow, repeatable failure mode that correlates with sustained sequential writes on partially full drives.
• Phison and Microsoft’s large‑scale lab and telemetry efforts did not find evidence of a systemic, production‑firmware bug tied to KB5063878; Phison’s published testing totals (4,500+ hours, 2,200+ cycles) support that negative finding. (tomshardware.com, bleepingcomputer.com)
• The pre‑release/engineering firmware hypothesis plausibly reconciles these points — it explains why community rigs saw repeatable behavior while vendor verification did not — but it remains unproven without vendor‑published forensic proof. Treat that explanation as a strong lead, not a settled conclusion.

Risk to the broad installed base appears to be low based on current telemetry and vendor testing, but the impact of the narrow failure (data corruption, inaccessible drives) is high. That combination demands conservative operational behavior and rapid vendor transparency until a formal, auditable root cause is published.

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Conclusion​

The “Windows 11 SSD killing” saga evolved quickly from alarm to investigation and now to a nuanced forensic debate. The industry responded: independent test benches raised a credible signal, vendors mobilized extensive lab resources and reported null results at scale, and researchers proposed a targeted, supply‑chain‑adjacent hypothesis involving engineering firmware on a small subset of drives. The story is not closed — definitive, auditable evidence (NVMe traces, controller logs tied to serial ranges, or supply‑chain confirmations) is required to move from plausible explanation to proven root cause.
Until that evidence appears, the right posture for users and IT teams is conservative: back up, avoid large sustained writes on potentially affected systems, apply firmware only from vendor channels, and preserve failed devices for diagnostics. For the broader PC ecosystem, this incident should prompt better cross‑vendor testing, improved telemetry for rare but catastrophic events, and stricter controls around firmware programming and distribution. The incident is both a narrow technical puzzle and a larger lesson in managing complexity when millions of systems, dozens of vendors, and hundreds of firmware revisions must work together flawlessly. (tomshardware.com)

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Source: Neowin Phison confirms potential real reason for "Windows 11 SSD killing and corruption" bug
Source: Fudzilla.com Blame for borked SSDs shifts again

Microsoft’s August Windows 11 patch is no longer the prime suspect in the recent wave of “vanishing” NVMe drives — mounting evidence points to pre‑release controller firmware and supply‑chain provenance, not the KB5063878/KB5062660 updates themselves, as the root trigger in the cases investigated so far.

Background / Overview​

In mid‑August, social posts and a small number of high‑visibility community tests claimed that the Windows 11 24H2 August cumulative update (commonly tracked as KB5063878, with a related preview KB5062660) caused NVMe SSDs to disappear during large, sustained file writes. The symptom set was dramatic: drives would momentarily vanish from File Explorer and Device Manager during multi‑GB transfers, vendor diagnostic utilities would fail to reach the controller, and in some reports the partition returned as RAW or required reformatting to restore basic functionality. Early reproductions consistently cited sustained sequential writes of roughly 50 GB or more to drives already around ~60% used.
Vendors and platform teams quickly triaged the reports. Microsoft opened an investigation and published a service alert saying its telemetry and controlled testing found no evidence of a platform‑wide link between the August update and a spike in storage failures. Phison — the NAND controller vendor implicated in many early reports — ran an extensive validation program and likewise reported it could not reproduce a systemic failure on production firmware after more than 4,500 hours and thousands of test cycles. (support.microsoft.com, pcgamer.com)
Over the following days the story evolved from “Windows killed my SSD” into a more nuanced cross‑stack problem statement: reproducible community tests existed, but vendor telemetry and lab validation indicated no fleet‑level regression. That tension is the essential frame for understanding the final twist: community researchers traced the failures to engineering preview (pre‑release) firmware present on a limited set of retail units used in their tests — firmware that Phison and partners say was not the finalized code shipped to consumers. (techspot.com)

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Timeline: how the incident unfolded​

• August 12 — Microsoft ships the combined SSU + LCU for Windows 11 24H2 (community tag: KB5063878). Early public release notes do not list a storage regression. (support.microsoft.com)
• Mid‑August — an initial user report from Japan and follow‑up hobbyist labs show repeatable drive disappearance during sustained writes on certain drives; social media spreads the claim that the update “bricked” SSDs.
• Aug 18 onward — Phison is alerted, conducts multi‑thousand‑hour test campaign; Microsoft conducts telemetry and lab checks. Both report no fleet‑level signal tying the update to widespread failures. (pcgamer.com, pcworld.com)
• Late August — a hardware enthusiast group (PCDIY!) reports the affected sample drives were running engineering preview firmware, not finalized retail firmware. Phison confirms it examined the community samples and could replicate the failure when using the non‑retail engineering firmware, while production firmware on consumer models did not fail under the same test load. Independent specialist outlets and vendor statements consolidate this finding. (windowsreport.com, tomshardware.com)

This timeline shows a common pattern in modern incident response: rapid community reproduction draws vendor attention, vendors run controlled lab programs, and a cross‑stack forensic picture emerges that may be narrower and more complex than the original viral claim.

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What the labs found: symptoms, reproducibility, and provenance​

Symptoms and workload fingerprint​

Community labs established a consistent failure fingerprint:

• A sustained sequential write of tens to hundreds of gigabytes (commonly ~50 GB+) to the target NVMe device.
• Target drives at elevated occupancy (reports cluster around ~60% used).
• During the transfer the drive stops responding to I/O, disappears from Windows management interfaces, and vendor tools report unreadable SMART or controller telemetry.
• Reboot often restores visibility; in a minority of tests the partition table or written data is corrupted and requires vendor recovery steps.

These characteristics point away from a simple filesystem bug and toward a controller‑level hang or firmware crash — the host loses the device while in‑flight writes may be dropped or partially committed.

Reproducibility vs. scale​

The crucial distinction that emerged is reproducibility on individual benches versus reproduction at scale. Community test benches repeatedly recreated the failure using a consistent recipe: fill level + heavy sustained writes + specific drive samples. At the same time, Phison and Microsoft reported that their large‑scale, controlled test programs — encompassing thousands of hours and hundreds of drive samples — did not reproduce a fleet‑scale failure on production firmware. That mismatch demanded a deeper look at which firmware versions the community benches were testing. (guru3d.com)

Provenance: engineering firmware vs. production firmware​

PCDIY! and other community investigators discovered that the drives used in several failing reproductions were running an unfinished, engineering preview firmware build. Those early engineering images are used for validation and development, and are not supposed to ship in retail units. Phison engineers later acknowledged the samples contained non‑retail firmware and could reproduce the crash using the same engineering image, while consumer‑shipped firmware did not exhibit the same failure under identical stress tests. This distinction reconciles the reproducibility on a narrow set of benches with the broader vendor telemetry showing no platform‑wide failure. (windowsreport.com, tomshardware.com)
Note: specific internal build names or suffixes (for example a variant described in some posts as “PS5026‑E26‑52”) appear in semi‑public forum dumps and community posts; such exact build identifiers are sometimes vendor‑internal and not always independently verifiable. Treat specific internal revision strings as provisional unless confirmed by an official vendor advisory.

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Technical analysis: why firmware provenance can matter more than an OS patch​

SSDs are systems‑on‑silicon: controller ASIC, DRAM (or HMB), flash channels, firmware and FTL logic. The host OS interacts with an SSD through the NVMe protocol and driver stack, but much of the critical behavior (GC, mapping tables, power and thermal protections, internal caches) is controlled by on‑device firmware. A small change in host I/O timing or flush semantics introduced by an OS patch can expose latent firmware bugs — if that firmware contains code paths not fully hardened or intended only for validation.
Key technical points:

• FTL and SLC cache behavior: Sustained writes to a near‑filled drive stress the FTL, cause SLC caching to saturate, and increase internal garbage collection. If firmware incorrectly handles command ordering or timeouts under those stress profiles, it can hang or corrupt mapping metadata.
• Thermal and power protections: Modern high‑performance controllers (notably PCIe 5.0 E26 family) generate substantial heat and rely on expected thermal management strategies and host cooling. Engineering firmware may exercise aggressive performance modes that, without proper heatsinks or expected thermal thresholds, can trigger fail‑safe shutdowns or improper throttling. (phison.com, tomshardware.com)
• Host‑side timing and NVMe semantics: If an OS or driver change alters command queuing behavior, outstanding IO counts, or how flush/fua semantics are processed, firmware that relies on older timing guarantees can hit race conditions or timeouts.
• Provenance and factory provisioning: Drives intended for validation or engineering fulfillment are sometimes provisioned with non‑production firmware for pre‑shipping tests. If such samples inadvertently make it into retail or test pools, they can confuse field signals.

In short: a host update can expose a firmware bug, but that does not mean the host update is the fault — it can be the trigger that reveals a latent controller/firmware defect present in specific engineering builds.

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What vendors reported and how the evidence fits​

• Microsoft: concluded its internal testing and telemetry review found no connection between KB5063878 and a measurable increase in disk failures across its fleets. Microsoft invited affected users to submit diagnostics and continued monitoring. (support.microsoft.com, pcworld.com)
• Phison: publicly stated it ran an extensive validation campaign (commonly reported as >4,500 hours and ~2,200 test cycles across implicated device sets) and could not reproduce a systemic failure on consumer production firmware. Phison also investigated community samples used in successful reproductions and confirmed those particular units were running engineering, pre‑release firmware which did fail under the reproduced stress — and the company could replicate the failure when the engineering firmware was used, but not when production firmware was applied. Phison additionally advised proper thermal management for PCIe Gen5 E26 devices and worked with vendors to trace firmware provenance. (pcgamer.com, tomshardware.com)
• Community (PCDIY! and builders): documented repeatable failure recipes and captured logs showing the device disappearance pattern. Their tests were critical to locating the firmware provenance: the sample drives used in their benches were not on the final retail firmware. That forensic lead guided Phison to re‑examine the exact units. (windowsreport.com)

Taken together, the vendor and community evidence converge to a credible hypothesis: a small set of drives running engineering firmware exhibited instability when stressed by a specific host workload, which in public view coincided with the Windows update timeline. That coincidence led to initial attribution to the OS patch, but the deeper cross‑stack investigation has shifted the locus of causation to firmware provenance.

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Strengths of the investigation and where uncertainty remains​

Strengths​

• Independent reproducibility: community benches documented a clear and repeatable recipe to trigger the symptom set, which is strong investigative evidence in complex system incidents.
• Vendor lab validation: Phison’s large‑scale testing program (thousands of hours) and Microsoft’s telemetry reviews provide complementary, high‑quality negative controls that rule out a broad, deterministic regression across production firmware. (pcgamer.com, support.microsoft.com)
• Cross‑party confirmation: Phison engineers directly examined community sample units and confirmed the presence of non‑retail engineering firmware; reproducing the failure on those firmware images is a substantial evidentiary link. (windowsreport.com)

Remaining uncertainties and risks​

• Scope of affected retail units: while vendors say production firmware is not affected in tests, explicit published lists of serial ranges or batch advisories have not been uniformly issued by all SSD manufacturers. Without transparent supply‑chain disclosure it’s difficult to quantify how many units, if any, shipped into retail with engineering firmware. This is a forensics gap that matters for large fleets and data‑sensitive users.
• Irrecoverable data cases: a minority of field reports claim permanent data loss. While the majority of disappearances were transient, any mid‑write disappearance can corrupt data. For affected users, root‑cause attribution does not change the concrete outcome of lost files. That risk remains real for those few incidents.
• Potential for other controller families: early reports included drives using other controllers (InnoGrit, Maxio, etc.). The E26 family and Phison were heavily represented in community reproductions, but the incident underscores a broader truth: cross‑stack timing changes can surface latent bugs in diverse firmware implementations. Vendors must therefore remain vigilant.

Where claims are precise about internal firmware revision strings, factory serial batches, or the exact number of affected retail units, they remain partially unverifiable in public reporting until vendors publish formal advisories with RMA guidance and accountable batch metadata.

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Practical guidance for users, enthusiasts, and IT admins​

The episode is instructive: it is possible for OS changes to reveal latent hardware‑firmware defects, but that does not automatically mean the OS is defective. The defensive posture is practical and straightforward.

• Back up first, always. Data preservation is the only reliable protection against mid‑write corruption or device loss. Keep verified external or cloud backups before applying large updates or performing heavy transfers.
• Delay heavy write workloads after major updates. Avoid single‑session, sustained sequential writes (game installs, large archive extraction, cloning) immediately after applying system updates until vendor guidance is confirmed.
• Verify drive firmware and vendor tools. Use official vendor utilities to confirm firmware versions. Apply official production firmware updates only via vendor tools and after backing up critical data. If vendor advisories are published, follow their remediation steps.
• Preserve failed drives for vendor diagnostics. If you encounter a disappearance event, power off, do not format, and provide the drive to vendor support with logs and system traces. Forensic captures (ETW traces, kernel logs, SMART dumps) are invaluable.
• For enterprises: stage updates using representative hardware pools. Use WSUS/SCCM ringed deployment and monitor vendor release health and firmware advisories before broad rollout.

Administrators should prioritize staging and representative validation: a single infected sample from a small subset of devices can create operational risk when updates are deployed broadly without representative testing.

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Broader lessons for the PC ecosystem​

1. Cross‑stack transparency matters. Operating system vendors, controller vendors and drive OEMs need coordinated forensic disclosures that include test recipes (drive fill %, write profile, logs) and firmware revision lists. Public, auditable post‑mortems restore trust and reduce speculation.
2. Supply‑chain hygiene is critical. Units with engineering firmware should never reach retail. If they do, vendors must be able to trace serial/batch metadata and publish clear RMA or advisory programs. The lack of such traceable disclosures prolongs uncertainty.
3. Cooling and form‑factor reality for Gen5 SSDs. Modern high‑speed controllers (for example Phison’s PS5026‑E26 family) generate enough heat that design expectations (heatsinks, motherboard cooling) matter — engineering firmware and test conditions that assume different cooling can produce misleading failure signals if used outside validated hardware configurations. (phison.com, tomshardware.com)

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Final assessment and conclusion​

The most responsible, evidence‑based reading of the public record today is this: the August Windows 11 updates (KB5063878/K5062660) were an observable trigger for a rare failure pattern reported by community testers, but not the root cause of an industry‑wide “SSD‑killing” regression. Community reproductions pointed investigators to a crucial provenance issue — several failing samples were running pre‑release engineering firmware. Phison’s exhaustive internal testing and Microsoft’s telemetry reviews corroborate that production, consumer‑shipped firmware did not exhibit the catastrophic failure in the same tests. (pcgamer.com, support.microsoft.com)
That conclusion is good news for most users: if you bought a retail NVMe SSD and have applied official vendor firmware and cautionary thermal measures (heatsink where required), your risk of encountering this specific failure is low. However, the episode leaves open concrete operational risks for the few users who actually experienced mid‑write data loss. Until vendors publish explicit, auditable batch/firmware advisories, some uncertainty will remain for those affected. Treat claims of “bricked drives” with healthy skepticism, verify firmware provenance on suspect units, and pursue vendor support for any drive that shows persistent failure after a reboot. (windowsreport.com)
Ultimately, this incident is a reminder that modern storage reliability is a cross‑stack property: OS patches, NVMe driver timing, controller firmware, factory provisioning and thermal design all interact. The right defensive strategy for users and administrators is simple: keep backups, stage updates, verify firmware, and insist on coordinated, transparent vendor disclosures when incidents cross the public sphere. The panic headlines that followed the August update overstated the immediate danger, but the technical lesson is durable: trust but verify — and demand traceability when hardware and firmware meet at scale.

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Source: TechSpot Windows 11 cleared of all charges for killing SSDs, the real culprit is faulty firmware