KB5063878 Windows 11 24H2: SSD Disappearances Under Heavy Writes Explained

The Windows update ecosystem once again landed in the headlines this month after community researchers and multiple publications raised alarms about KB5063878 — the August 12, 2025 cumulative update for Windows 11 24H2 — and claims that a sustained-write workload can make some NVMe SSDs disappear from the OS or leave data unrecoverable. Early evidence points to a reproducible failure profile (disappearance during long sequential writes, often around ~50 GB) that several enthusiast outlets and testers reproduced, but official vendor guidance narrows the root cause to compatibility between host HMB allocation behavior and specific SSD firmware on affected models. (hothardware.com) (support.microsoft.com) (guru3d.com)

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Background​

What shipped in KB5063878​

Microsoft released KB5063878 (combined SSU + LCU) for Windows 11 version 24H2 on August 12, 2025, identified as OS Build 26100.4946. The official release notes describe security and quality fixes and initially stated that Microsoft was “not currently aware of any issues with this update.” The KB page remains the authoritative record for package contents and release timing. (support.microsoft.com)

How the incident first surfaced​

Public attention spiked after an X (Twitter) user, identified in several reports as @Necoru_cat, posted a reproducible scenario: while performing a large sequential file transfer (example: updating a large Steam game), their SSD disappeared from Windows during the copy and, in some tests, subsequent reboots left the drive’s partition metadata corrupted and unreadable. That single-threaded investigation grew as other hobbyist testers reproduced similar disappearance symptoms under heavy, sustained writes. Publications such as Tom’s Hardware, NotebookCheck and Guru3D documented and amplified those community reproductions. (tomshardware.com, notebookcheck.net, guru3d.com)

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Overview: symptoms, scope, and immediate findings​

• Typical symptom — During a sustained large sequential write (community reports coalesce around roughly 50 GB written and/or drive utilization beyond ~60%), the target NVMe drive becomes unresponsive and vanishes from File Explorer, Device Manager and Disk Management. After that point, SMART/controller telemetry may be unreadable to vendor utilities. Reboot sometimes restores visibility, but files written during the failure window can be corrupted or missing. (tomshardware.com, notebookcheck.net)
• Who reported it — Early reproductions came from individual/hobbyist testers and community forums; specialist outlets then performed independent verification. These are not limited to a single brand or controller but show clustering around certain controller families (notably some Phison controllers) and DRAM-less designs. However, affected lists vary between testers, and not every drive using the same controller family is guaranteed to fail. (guru3d.com, notebookcheck.net)
• Short-term consequences observed — Drive disappearance, temporary or permanent data unreadability, BSODs in certain configurations (different symptom clusters depending on how the underlying firmware and OS interactions fail), and enterprise install failures related to WSUS/SCCM with error codes such as 0x80240069 in some deployment setups. Microsoft later acknowledged installation problems affecting WSUS/SCCM for this cumulative update. (windowslatest.com, bleepingcomputer.com)

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Technical primer: HMB, DRAM-less SSDs, and why sustained writes matter​

What is HMB and why does it matter here?​

Host Memory Buffer (HMB) is an NVMe feature that allows DRAM-less SSDs to use a small portion of host RAM to store mapping tables and metadata, improving performance for drives that forgo an on-board DRAM cache. Historically many systems and SSD drivers negotiated modest HMB sizes (for example ~64 MB in prior Windows builds for certain devices). Changes to host-side allocation policy or how Windows interacts with NVMe drives can exercise unusual internal paths in an SSD controller’s firmware, especially under long, sustained writes. (notebookcheck.net, tomshardware.com)

Sustained sequential writes stress different code paths​

A short burst of writes exercises cache and internal queues differently from a prolonged sequential stream. Sustained workloads increase internal garbage collection, queue depth, DMA traffic and thermal stress. Those conditions expose firmware race conditions or edge-cases that would remain latent in normal desktop use. Community reproductions show the problem reliably emerges with extended sequential writes in the 50+ GB range on some systems. That aligns with a controller-level hang or metadata corruption scenario rather than a simple OS file-copy error. (guru3d.com, notebookcheck.net)

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Who’s affected: models and controllers reported in community testing​

Multiple outlets and community collations list affected devices, but lists are inconsistent across tests — reflecting the complexity of host-device interactions and test-bench variability. Independent reporting has repeatedly flagged:

• WD / SanDisk NVMe models (WD Black SN770, WD Blue SN580, WD Blue SN5000, SanDisk Extreme) in earlier 24H2 incidents tied to HMB allocation changes. Vendors later issued firmware updates addressing those specific WD/SanDisk symptoms. (tomshardware.com, borncity.com)
• Drives using Phison controller families (examples named in community lists include PS5012-E12, E21T, E31T and others) were frequently flagged in the August 2025 KB incident, plus a smattering of other controllers in community reproductions. But this doesn’t mean all Phison-based drives are impacted — test results vary. (guru3d.com, notebookcheck.net)
• Additional models reported in community collations include Corsair Force MP600 (Phison E16), Kioxia Exceria Plus G4, Crucial P3 Plus, and others. NotebookCheck and Guru3D published specific lists based on the tests they reviewed. Those lists are useful triage pointers but not exhaustive. (notebookcheck.net, guru3d.com)

Important caveat: community tests used a single test bench configuration in some reproductions, so results may reflect a combination of motherboard firmware, CPU, BIOS settings (PCIe lane negotiation), memory timing and power/thermal profiles in addition to SSD firmware. The only authoritative “affected model” lists come from vendors once they validate the failure and publish firmware booter or advisories. (hothardware.com)

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Vendor and Microsoft responses: patches, blocks, and advisories​

• Microsoft: The KB page for KB5063878 formally documents the release (Build 26100.4946), and Microsoft later acknowledged related deployment problems (WSUS/SCCM install error 0x80240069). In the 24H2 rollout cycle vendors and Microsoft used upgrade-health blocks and compatibility holds to prevent the feature update on systems with known vulnerable firmware until fixes were available. Microsoft has published standard update-health guidance and applied selective blocks where vendor firmware updates are required before offering the feature update. (support.microsoft.com, bleepingcomputer.com)
• Western Digital / SanDisk: For the earlier HMB-related WD incidents tied to 24H2, Western Digital issued targeted firmware updates for specific SN770/SN580/SN5000 and SanDisk models. Those firmware revisions adjusted HMB handling and were explicitly recommended to users who experienced BSODs or install blocks. Tom’s Hardware and vendor dashboards were the primary recommended ways to update firmware. (tomshardware.com)
• Other vendors (Phison, Intel, etc.): Where community reporting pointed to Phison-based controllers, Phison and board partners investigated; some vendors issued firmware revisions or coordinated guidance for affected OEMs. In parallel, vendor and community testing narrowed the most likely failure modes (firmware edge-cases triggered by host behavior). (guru3d.com)

Across these responses, the consistent message to users was: back up first, update SSD firmware if a vendor patch exists, and avoid heavy sequential writes until you’ve confirmed compatibility. (tomshardware.com)

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Reproductions, testing methodology, and what we still don’t know​

What the independent tests showed​

Community testers and hobbyist researchers used long sequential file copies (large game installs, extracted archives, or synthetic sequential-write workloads) to reproduce the disappearance. Multiple outlets confirmed reproducibility for specific devices and controllers, with the common trigger pattern being long sustained writes around the 50 GB mark and elevated drive utilization. Some vendors and testers also noted that drives sometimes returned after a reboot but that in a minority of cases the partition table or metadata was corrupted beyond easy recovery. (tomshardware.com, notebookcheck.net)

Where uncertainty remains​

• The exact cross-product of firmware version + controller family + motherboard BIOS + CPU + memory timing that causes permanent corruption vs. transient disappearance is not fully enumerated in public reports. Test benches differed between testers and any single bench can introduce confounding variables. This makes it hard to claim a universal “Windows update bricked my SSD” narrative without careful root-cause validation. Multiple reputable outlets stressed that the pattern is real but the scope is still being refined. (hothardware.com, guru3d.com)
• A handful of highly publicized stories describe supposedly “bricked” SSDs; after deeper analysis many of those instances reflected driver/firmware recoverable states or corrupt partition metadata — important distinctions. True hardware bricking (irreversible controller flash corruption) is rare in these reports; the majority appear to be firmware/controller hangs and file-system metadata loss, not physical destruction of NAND or controller die. Nevertheless, the operational result for users — inaccessible files and non-booting systems — is functionally identical to a bricked drive until recovery succeeds. (hothardware.com, easeus.com)

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Practical, step-by-step guidance for affected users​

If you’re worried you might be impacted, follow this prioritized checklist. These steps aim to minimize risk and restore a safe configuration without assuming a corporate patch schedule.

• Back up critical data immediately. Use an external USB drive or cloud sync before attempting firmware updates or modifications.
• Check your current Windows build: Settings → System → About → OS build. If you have KB5063878 / OS Build 26100.4946, treat heavy writes cautiously. (support.microsoft.com)
• Identify the SSD model and firmware: Device Manager → Disk Drives or use vendor tools (WD Dashboard, SanDisk Dashboard, Samsung Magician, Crucial Storage Executive, etc.). Vendor tools will show firmware versions and may offer a direct firmware update. (tomshardware.com, guru3d.com)
• If your vendor has published firmware addressing Windows 11 24H2 issues, apply it per vendor guidance — but only after backing up. Vendor firmware updates sometimes carry a small risk of data loss; follow instructions exactly. (tomshardware.com)
• If firmware is unavailable and you need an immediate workaround, many community threads showed that limiting or disabling HMB reduced crashes. Advanced users changed registry keys such as HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorPort\HmbAllocationPolicy (values discussed in community threads included values to disable or limit allocation). This is a last-resort mitigation and can degrade performance; back up the registry and proceed cautiously.
• If a drive disappears mid-transfer, stop the transfer activity, note the symptoms and event log entries, and perform a graceful reboot. If the drive remains missing, vendor recovery tools may help but continued writes risk further corruption. (tomshardware.com)

Numbered safety reminder: firmware updates and registry tweaks are powerful tools — they can fix the problem but can also cause data loss if applied incorrectly. Always backup first and follow vendor instructions. (tomshardware.com)

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How to check whether the issue is a Windows-side regression or SSD firmware problem​

• Reproduce on a different test bench: if you can reproduce the failure across multiple motherboards and CPUs with the same SSD and Windows build, the likelihood the SSD firmware or controller has a latent bug increases. If the failure only appears on a single motherboard/CPU combination, investigate BIOS settings and PCIe lane negotiation (some posts pointed to BIOS auto-negotiation misconfigurations as confounders). (learn.microsoft.com, techpowerup.com)
• Test with different firmware versions: where vendor firmware revisions exist, applying the patched firmware and rerunning the workload is a straightforward way to confirm whether the vendor fix addresses the symptom. (tomshardware.com)
• Keep an eye on Event Viewer: look for NVMe/controller related errors, I/O timeouts or storahci/stornvme controller messages that correlate with the disappearance. Those logs help vendors and Microsoft triage root causes. (tomshardware.com)

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Broader takeaways for IT teams, integrators, and enthusiasts​

• The incident is a reminder that OS-level storage stack changes can expose latent firmware bugs in devices that previously behaved. The interaction of host-side changes and embedded device firmware is a perennial risk for complex ecosystems where independent vendors iterate on different cadences. (guru3d.com)
• Rollout protections (upgrade-health blocks and staged rollouts) are essential. Microsoft and vendors used selective blocks while firmware updates rolled out — an important safety valve that prevents broader population exposure. Enterprises should mirror that caution: test updates in controlled rings and use WSUS/SCCM to stage deployment. (bleepingcomputer.com)
• Backup discipline and robust pre-update validation remain the simplest and most effective user protections. No browser article or registry tweak replaces a verified backup. (easeus.com)

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Strengths, limits, and risks in the current public reporting​

• Strengths: Multiple independent reproductions across hobbyist testers and specialist outlets make the report credible and actionable. Vendor firmware fixes and Microsoft deployment blocks demonstrate a functioning remediation process that reduced the risk of a widespread, permanent bricking event. (guru3d.com, tomshardware.com)
• Limits: Much of the early evidence comes from single-test benches and user-contributed logs; while consistent patterns emerged (sustained writes ~50 GB, certain controllers), the universe of affected firmware+hardware combinations is still being refined. That means blanket claims that “the Windows update bricked SSDs” overstate the evidence; a significant portion of reports point to firmware hangs or metadata corruption rather than irreversible hardware destruction. (hothardware.com, notebookcheck.net)
• Risks to users: The most immediate risk is data loss from in-progress writes if a disappearance occurs mid-transfer. Even if a drive returns after a reboot, data written during the failure window may be corrupt. Applying vendor firmware updates without a backup introduces an additional risk vector. (tomshardware.com)

Where claims are not yet verifiable — for example, single-case claims of non-recoverable, hardware-level bricking — those should be flagged as unresolved until vendors or labs reproduce the exact hardware-failure mode under controlled conditions. The public record to date supports a high-impact but mostly firmware-level failure profile rather than wholesale hardware destruction in bulk. (hothardware.com, guru3d.com)

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Final analysis and recommendations​

The weight of evidence indicates that KB5063878 can expose latent firmware/controller edge-cases in certain NVMe SSDs during sustained sequential writes, producing drive disappearance and, in some cases, data corruption. Multiple reputable outlets and community testers independently observed the pattern; Microsoft’s KB and deployment controls plus vendor firmware updates addressed many of the most pressing configurations. However, the landscape is nuanced: not all drives with the same controller are affected, and test-bench variability complicates definitive lists. (support.microsoft.com, guru3d.com, tomshardware.com)
For Windows users and administrators the practical, defensible path is:

• Prioritize backups before any update or large writes.
• If you rely on high-volume, sustained file transfers, confirm your drive’s firmware is up to date with vendor-supplied fixes before installing KB5063878-level updates.
• If you encounter symptoms (drive disappearance or BSOD during large writes), stop heavy writes, document Event Viewer logs, update SSD firmware if available, and, if necessary, apply the community or vendor mitigations to limit HMB allocation as a temporary measure.
• Enterprise admins should continue to use staged rollouts (WSUS/SCCM) and monitor vendor advisories and Microsoft release-health notices before broad deployment. (tomshardware.com, bleepingcomputer.com)

This episode reinforces a simple principle: in a heterogeneous PC ecosystem, coordinated testing between OS vendors and hardware/firmware suppliers is vital. When it fails, the damage is rarely mysterious — it’s usually the natural consequence of a host making a new or different set of assumptions that expose an embedded device’s latent corner-case.

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Windows users should remain vigilant but not alarmed: the problem is serious for affected configurations, but the combination of community reporting, vendor firmware fixes and Microsoft’s deployment protections substantially reduced the chance of a mass “bricking” event. Where uncertainty persists, follow vendor guidance, back up first, and apply the measured mitigations above. (hothardware.com, tomshardware.com, guru3d.com)

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Source: HotHardware Is A Nasty Mysterious Windows Update Bug Really Bricking These SSDs?

 

[ChatGPT]

Microsoft’s August cumulative appears to have introduced a serious storage regression: numerous Windows 11 24H2 systems report that SSDs — and in some cases HDDs — can disappear from the OS during heavy, sustained writes, leaving drives inaccessible and, in several user-tested cases, permanently corrupted or unrecoverable. (tomshardware.com, guru3d.com)

Background / Overview​

Over the last week, community testers, forum posters, and a handful of technology outlets documented a repeating failure mode that surfaces during large sequential write operations (commonly observed with transfers in the 50–100 GB range). In affected systems, the target storage device simply vanishes from File Explorer, Device Manager and, in multiple reports, from the platform firmware (BIOS/UEFI), making ordinary recovery attempts impossible. (tomshardware.com)
Initial public attention began when an X (Twitter) user documented a reproducible sequence that caused an NVMe drive to go missing while updating a large game; subsequent experimenters expanded that initial dataset into tests covering more than a dozen drives and multiple controller families. Independent outlets have since reproduced or collated the user findings and reported similar symptoms across a range of SSD models. (tomshardware.com, neowin.net)
Microsoft shipped this code as part of the August 2025 security cumulative (listed as KB5063878, OS Build 26100.4946 for Windows 11 24H2). The Microsoft support page for KB5063878 does not list a known storage regression at the time of publication and currently states that “Microsoft is not currently aware of any issues with this update,” even though multiple community reports say otherwise. (support.microsoft.com, techradar.com)

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Which systems and workloads are affected​

Typical workload pattern​

• The failure is most consistently reproduced during large, sustained sequential writes — examples include installing or updating large games, copying multi-GB archives and decompressing them on the target volume, or cloning operations. Several reproduce reports used ~50–100 GB test files and multi-file archive extraction as a trigger. (tomshardware.com, neowin.net)
• Reported reproductions frequently describe the drive as being ~60% full when the bug occurs, but this is not a strict precondition; other testers triggered the condition on drives with different utilization levels. The 60% figure appears to be an observational pattern from community testing rather than a proven limit of any OS component. (tomshardware.com)

Hardware patterns: controllers, DRAM-less and beyond​

• Early observations flagged Phison-based controllers as disproportionately represented among affected drives. That association prompted manufacturers to begin internal reviews and outreach with partners. (tomshardware.com)
• Crucially, the problem is not limited to a single controller vendor or to DRAM-less designs. Community test reports and aggregated lists include drives powered by multiple controllers and vendors, with both DRAM and DRAM-less devices showing failures in different test setups. This suggests the issue likely arises from an interaction between OS-level I/O/driver behaviour and a subset of firmware/controller implementations rather than a single broken controller SKU. (tomshardware.com, guru3d.com)

Persistence and recovery characteristics​

• In many cases, a reboot temporarily recovers the device. In other incidents, the drive does not return after reboot and becomes invisible even in system firmware (BIOS/UEFI), which is a strong indicator that data structures or the controller state has been corrupted to the point normal enumeration cannot proceed. Some affected testers reported permanent loss of partition data after reproducible failures. (tomshardware.com, guru3d.com)

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Repro steps and independent verification​

What community testers did​

Multiple independent testers published step-by-step sequences that reliably produced the failure in their environment:

• Copy a large game or multi-GB folder (often ~90 GB) from one volume to a target SSD.
• Create a compressed archive of ~60+ GB comprising many files; write the archive to the target SSD.
• Decompress the archive on the target SSD and allow the drive to absorb a sustained write load.
• Observe enumeration loss — the drive disappears from Windows and in some reports from BIOS/UEFI. (tomshardware.com, neowin.net)

These procedural reports allowed outlets and other community members to reproduce similar symptoms, increasing confidence that the observations were not isolated hardware failures. However, testers also stress the limits of community validation: different motherboards, firmware revisions, drivers, and environmental factors can alter reproducibility. (tomshardware.com)

What the lab-style re-tests show​

In one multi-drive round-robin test, a tester evaluated 21 drives and observed that roughly half became inaccessible during heavy writes, with at least one reported as unrecoverable across multiple reboots. The mixed results across that small sample highlight two things: this is neither universal nor entirely predictable, and it can produce permanent data loss on a portion of affected devices. (tomshardware.com, guru3d.com)

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Vendor and Microsoft responses — what’s confirmed, what remains open​

Phison’s response​

Phison — a leading NAND controller supplier repeatedly cited in the community thread — issued a measured acknowledgment that it had been made aware of issues affecting certain controllers following the KB5063878 (and KB5062660) updates and that affected controllers were under review as they worked with partners. The statement framed the problem as industry-wide, invoked a review and collaboration, and promised further advisories as investigations proceed. (tomshardware.com)

Microsoft’s official position​

Microsoft’s KB page for KB5063878 lists the update, describes its fixes and improvements, and states there are no currently known issues for that update at the time of the support posting. Separately, Microsoft has publicly tracked and resolved other, unrelated issues with the August update (for example, a Group Policy-based Known Issue Rollback addressing WSUS/SCCM installation errors). As of the latest public Microsoft update, the storage regression affecting SSDs has not been reflected on the Microsoft “known issues” list for KB5063878. (support.microsoft.com, neowin.net)

Media and community confirmations​

Independent technology outlets and community forums have documented the problem and reproduced the failure mode in multiple environments. Outlets that aggregated test data and vendor commentary include mainstream tech publications and enthusiast sites; these organisations cross-checked user logs, reproduction steps and vendor statements while warning users to take preemptive precautions. (techradar.com, guru3d.com)

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Technical analysis: probable root causes and why this matters​

Why a Windows update can expose storage firmware flaws​

Modern SSDs rely on cooperative behaviour between OS drivers, NVMe stack implementations, and device firmware to manage mapping tables, garbage collection, and caching. Some lower-cost SSDs use the Host Memory Buffer (HMB) feature to outsource cache tables to system RAM instead of onboard DRAM. When sustained writes exercise controller logic and HMB mappings heavily, any subtle race, memory corruption or degraded command path behavior can cause the controller to enter a non-responsive state or to corrupt on-drive metadata. (windowsforum.com, tomshardware.com)
Although HMB and DRAM-less architectures are a plausible locus for a failure mode, reports including drives with onboard DRAM and different controller families indicate the bug is more likely an interaction — potentially within Windows’ storage stack — that triggers controller firmware edge cases. In short, the update may have altered timing, caching or I/O-flushing behavior long enough or in a way that some firmware versions are not resilient against. (windowsforum.com, guru3d.com)

Why the drive disappears from BIOS too​

A drive that disappears from BIOS/UEFI typically means the controller no longer responds to enumeration or has corrupted its NVMe namespaces/metadata to a state the platform firmware cannot parse. When a drive is only invisible to the OS but still visible to firmware, software-level resets can often restore access. The fact that some drives vanish from firmware indicates more severe controller-level corruption or an irreversible mapping failure — which explains why some cases result in permanent data loss. (tomshardware.com, guru3d.com)

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Risk assessment: who should be most concerned​

• Desktop and laptop users who store critical data on a single drive without recent backups are at greatest risk. The community reports show that the bug can cause permanent data loss for some devices. (tomshardware.com)
• Systems using SSDs as destination volumes for large writes (game installs, content creation scratch disks, local backup targets) face elevated risk because the trigger is sustained sequential write IO. (tomshardware.com)
• Enterprise and IT administrators must consider the potential for latent failures on client and workstation fleets. Even if the failure rate is low, the operational and data-protection impact can be significant if large work batches are performed en masse. (guru3d.com)
• Systems with older or unpatched drive firmware remain at higher risk if vendor firmware contains edge-case bugs that have since been addressed. Conversely, newly shipped firmware may also contain regressions; the key point is that firmware version influences risk. (guru3d.com)

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Immediate mitigation and risk-minimization steps​

The following steps prioritize data safety and practical mitigation while vendor investigations continue.

• Back up critical data immediately.
• Create a full copy of any irreplaceable files on a separate, known-good storage device (external drive, network share, or cloud). Do not perform large write operations to at-risk drives until the situation is clarified. (tomshardware.com, neowin.net)
• Pause installing the August 2025 cumulative (KB5063878) if it is not already applied.
• For Windows Update, use the built-in “pause updates” feature to delay automatic installation. Enterprise environments should hold the patch in WSUS/SCCM until vendors publish guidance. Note: Microsoft’s combined package includes a servicing stack update, which complicates uninstall paths; consult vendor channels before attempting package removal. (support.microsoft.com, neowin.net)
• Avoid heavy sequential writes to potentially affected drives.
• Postpone large game updates, archive extractions, cloning and any bulk copy tasks targeting suspect media until manufacturers and Microsoft provide a definitive fix. (techradar.com)
• Update SSD firmware and motherboard BIOS (where available).
• Check the SSD vendor’s support pages and download the latest firmware only from the manufacturer. Update your system BIOS/UEFI to ensure platform stability. If a vendor issues a rollback or specific advisory, follow their instructions precisely. (tomshardware.com, guru3d.com)
• If your drive becomes inaccessible, do not write more data to the device.
• Writing to a drive after corruption increases the likelihood of permanent loss. Power down the system and consult professional data recovery vendors if the data is valuable. (tomshardware.com)
• Consider hardware-level diagnostics before assuming a software fix will resolve the issue.
• Use vendor diagnostic utilities and SMART readers to snapshot drive state before attempting recovery; these logs will be valuable when filing a support request. (guru3d.com)

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Recovery techniques and what to expect​

• Soft recovery attempts: restart the machine, power-cycle the drive (remove and re-seat an M.2 module or power-cycle a SATA/HDD), or try the device in a different port/system. These actions can restore access in some cases but are not guaranteed. (tomshardware.com)
• Firmware-level or vendor tools: some vendors provide specific utilities to reinitialize or repair firmware metadata. These tools may restore drive visibility but can risk data loss; only use them after creating a forensic image or with vendor guidance. (guru3d.com)
• Professional recovery: if the drive contains business-critical or irreplaceable data, contact a reputable data recovery service. Do not perform repeated write-heavy operations that could overwrite salvageable metadata. (tomshardware.com)

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Guidance for IT admins and power users​

• Block or defer KB5063878 centrally if you manage endpoints that perform heavy writes, and communicate a clear backup policy to users before applying cumulative updates. Use Known Issue Rollback (KIR) or Group Policy controls where Microsoft provides them for other update-related problems. (neowin.net)
• Inventory drive firmware across fleets: collect vendor, model and firmware revision metadata using endpoint management tools and cross-reference with vendor advisories as they’re released. Prioritise firmware updates for devices that handle large data workloads. (guru3d.com)
• Create or reassess backup cadence: ensure that endpoints performing high-volume writes have rapid backup or snapshot protection so that a single drive failure does not result in unrecoverable data loss. (tomshardware.com)

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What remains unknown and how the situation may evolve​

• Causation vs. correlation: while multiple reproducible tests point to KB5063878 (and linked July updates) as a common trigger or enabling condition, the exact causal chain — whether the update changes OS timing, storage-driver behavior, Defender caching, or another kernel I/O surface that exposes firmware bugs — has not been independently verified in a controlled, vendor-backed lab at publication time. This means the community observations are strong warning signals but not a formal root-cause diagnosis. Flagged as unverified until vendors and Microsoft publish technical post-mortems. (tomshardware.com, guru3d.com)
• Scope: current reporting suggests a minority of drives reproduce the failure, but the real-world percentage across global hardware permutations is unknown. The conservative course is to treat all susceptible models as at-risk until firmware updates or Microsoft remediation guidance declare otherwise. (techradar.com)
• Vendor fixes vs. OS remediation: remediation could come from SSD vendors pushing firmware updates that harden controllers against the observed OS behavior, or from Microsoft adjusting driver, NVMe stack, or Defender components to avoid triggering fragile controller states. It may require coordinated fixes from both sides. Phison’s public acknowledgement that it’s “working with partners” indicates vendor engagement but not an immediate cure. (tomshardware.com)

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Practical recommendations — checklist​

• Back up now: copy all critical data off drives that might be affected.
• Pause cumulative updates until vendor guidance is available.
• Avoid large writes and game/patch installs on potentially vulnerable drives.
• Collect drive model + firmware data if you manage multiple systems.
• Update SSD firmware and BIOS only when a vendor explicitly identifies a fix; keep copies of current firmware and recovery plans.
• If a drive disappears, stop further writes and consider professional recovery if the data is important.

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Conclusion​

The recent community-discovered storage regression associated with the August 2025 Windows 11 cumulative (KB5063878) is a high-severity, low-frequency event: it can cause catastrophic data loss for some users while remaining invisible to others. Multiple independent reproductions, vendor acknowledgements that they are investigating, and mainstream coverage all combine to justify immediate, conservative action: back up critical data, avoid heavy writes on affected machines, and await coordinated remediation from storage vendors and Microsoft.
Until vendors publish firmware updates or Microsoft publishes a definitive root-cause and patch, the safest posture for home users and administrators is to assume risk exists and take preemptive protective steps. The interaction between modern OS storage stacks and ever-more-complex SSD firmware is again shown to be a brittle boundary — one that requires fast coordination between OS maintainers and device manufacturers when large-scale updates alter timing and behavior. (tomshardware.com, guru3d.com, support.microsoft.com)

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Source: Petri IT Knowledgebase Windows 11 Update Bug Triggers SSD Failures, Data Loss