Windows 11 KB5063878: SSD Failures Under Heavy Writes (50GB+)

Microsoft’s August cumulative for Windows 11 — released as KB5063878 (OS Build 26100.4946) — is now at the center of a rapidly developing reliability story: independent testers and multiple tech outlets report that, under sustained large writes (commonly cited around 50 GB and above), some NVMe SSDs can become unresponsive, disappear from Windows, and in a minority of cases return corrupted or unreadable — symptoms that amount to real data‑integrity risk for affected users. (tomshardware.com) (igorslab.de)

Background / Overview​

Microsoft published KB5063878 as the August 12, 2025 cumulative update for Windows 11, version 24H2 (OS Build 26100.4946). The public Microsoft support entry lists the security and quality fixes in the release and, at the time community reports began to surface, stated that Microsoft was “not currently aware of any issues with this update.” (support.microsoft.com)
Within days of the rollout, hobbyist testers and multiple specialist outlets independently reproduced a consistent failure profile: during extended, sequential write workloads — typically when copying or installing very large files or folders — certain SSDs stop responding and vanish from File Explorer, Device Manager and Disk Management. In many reproductions the controller telemetry or SMART attributes are no longer readable to vendor utilities; in a smaller number of reports the affected volume returns but contains corrupted, missing, or inaccessible data. That pattern has been reported around sustained transfers of roughly 50 GB and when drive/controller utilization climbs above ~60%. (guru3d.com) (notebookcheck.net)
This is not a theoretical performance bug: the operational fingerprint is a controller-level hang or lockup that makes the device invisible to the host, which — depending on how the write was committed — can leave files in a partially written or inconsistent state.

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What the patch actually is (and what it isn’t)​

The official release​

• KB5063878 is a combined Servicing Stack Update (SSU) + Latest Cumulative Update (LCU) for Windows 11 (24H2), distributed on August 12, 2025. The KB page details file lists, component changes and security fixes. Microsoft’s public page did not list a storage-device regression as a known issue at the time early community reports surfaced. (support.microsoft.com)

What community testing uncovered​

• Independent reproductions consistently associate the failure with sustained, sequential writes and higher drive utilization.
• The symptom set points to the SSD controller becoming unresponsive or the drive being removed from the OS topology rather than the host simply slowing or throwing a recoverable I/O error. (igorslab.de) (tomshardware.com)

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Symptoms and how failures present in the wild​

Commonly reported symptoms​

• Sudden disappearance of an SSD from File Explorer, Device Manager and Disk Management while a large copy or install is running. (tomshardware.com)
• Event Viewer showing storage controller, NVMe or I/O error messages near the time of failure. (guru3d.com)
• SMART and controller telemetry becoming unreadable to vendor utilities after the event. (igorslab.de)
• Reboot sometimes restores device visibility, but data written during the failure window can be corrupted or missing.

Typical trigger profile​

• Sustained sequential writes of roughly 50 GB or more, especially when the target drive is already substantially utilized (community reports indicate ~60% or higher). This behavior shows up during large game installs or archive extractions — real‑world tasks that routinely move tens of gigabytes of data. (notebookcheck.net) (borncity.com)

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Which drives and controllers are implicated (and what’s still uncertain)​

Early community collations and independent testers have repeatedly flagged a cluster of devices and controller families, but there is no single definitive list and not every drive with the same controller is affected.

• Drives and controller families often mentioned in reporting:
• Corsair Force MP600 (Phison E16). (igorslab.de)
• SSDs built around Phison controller families such as PS5012‑E12, E21T, E31T and others. (notebookcheck.net)
• SanDisk Extreme Pro M.2 NVMe (reported in some lists despite not using a Phison controller). (guru3d.com)
• A scattering of other models (KIOXIA Exceria Plus G4, Fikwot FN955, Crucial P3 Plus, WD Blue SN5000) appeared in community test lists. (notebookcheck.net)

Important nuance: the pattern is not strictly limited to Phison-based drives. Several non-Phison models appear in early test tables, suggesting the problem is triggered by a host‑side change interacting with particular firmware behaviors rather than a single manufacturer’s hardware fault. That observation makes root‑cause attribution more complex and argues for vendor + Microsoft telemetry to reach a final determination. (igorslab.de) (guru3d.com)

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Technical analysis — plausible mechanisms​

Multiple independent analysts and community engineers have converged on a small set of plausible mechanisms. None are yet confirmed by Microsoft or the SSD vendors, but the technical fingerprint lines up with these hypotheses:

• Host Memory Buffer (HMB) and allocation changes. Previous Windows 11 24H2 interactions showed that changes in how Windows allocates HMB to DRAM‑less NVMe SSDs can expose firmware limits or race conditions. A larger HMB allocation or altered timing could put some DRAM‑less controllers into edge conditions.
• NVMe command/timing regression in the storage stack. Small kernel-side changes in buffering, command ordering or DMA timing under sustained sequential writes can expose latent controller bugs that only appear under long, high‑utilization workloads. The resulting controller hang would present as a disappeared drive to the host. (guru3d.com)
• Controller firmware edge cases under high utilization. SSD controllers manage mapping tables, garbage collection, wear leveling and thermal throttling. Extended big writes stress those subsystems; a firmware bug triggered by altered host behavior can cause the controller to lock up or fail to respond. (igorslab.de)

These mechanisms are not mutually exclusive — a host-side regression can change I/O timing or caching behavior in ways that reveal controller firmware defects. The distribution of affected models in community tests suggests the host change is a plausible common denominator, but vendor firmware remains a likely remediation vector if specific controller code paths are failing.

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Verification status and official responses​

• Microsoft’s KB page for KB5063878 lists the update and the build number and, at time of the early reports, stated that Microsoft was not aware of any issues with the update. That means an official “known issues” entry explaining or acknowledging the storage symptom had not been posted when initial reporting occurred. (support.microsoft.com)
• Major enthusiast and hardware outlets (Tom’s Hardware, Igor’s LAB, Guru3D, NotebookCheck, BornCity) documented community reproductions and flagged the same symptom profile. These outlets independently confirmed the trigger characteristics and provided aggregated device lists from early testers. (tomshardware.com) (igorslab.de) (guru3d.com)
• As of reporting, SSD vendors had not universally issued a single, consolidated advisory about KB5063878; vendor responses were staggered and — in many cases — limited to firmware‑update notices for earlier 24H2 compatibility problems. That heterogeneity underscores the need for coordinated telemetry from Microsoft and individual vendors to produce a definitive fix. (borncity.com)

Caveat: community tests and journalist reproductions are strong early indicators, but conclusive, root‑cause proof requires vendor/Microsoft telemetry and a tested patch or firmware. Treat community lists as investigative leads rather than an exhaustive recall list.

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Immediate risk assessment — how bad is this for the average user?​

• Prevalence: early reporting indicates a small but significant cluster of reproducible incidents rather than a global, immediate failure across the entire Windows installed base. The practical risk is concentrated on systems performing large sustained writes to drives that are on community watch lists. (notebookcheck.net)
• Severity: when the condition occurs, the impact can be severe. Files being written during the failure window are at real risk of corruption or loss; some reports describe drives becoming inaccessible even after reboot. That elevates the incident from mere inconvenience to a potential data‑loss event for affected users. (guru3d.com)
• Reproducibility: community reproductions demonstrate that the symptom can be triggered reliably on specific system+drive+firmware combinations, which strengthens the claim that the KB is a causal factor — though causality needs final confirmation from Microsoft and vendors. (igorslab.de)

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Practical mitigation steps (consumer and prosumer)​

Take the following conservative, actionable steps immediately if KB5063878 is installed on a system that uses NVMe SSDs, especially if those drives are on community watch lists.

• 1.) Back up critical data now. The top priority is preventing irreversible loss; copy high‑value files to an external drive or cloud storage before performing large writes. (notebookcheck.net)
• 2.) Avoid sustained large writes (game installs, large archive extraction, bulk media copies) to suspect drives until vendor or Microsoft guidance arrives. Community reproductions show the issue primarily during extended sequential writes near ~50 GB. (guru3d.com)
• 3.) Check Windows build and the KB. Run winver or check Settings → Windows Update → Update history to confirm whether KB5063878 (Build 26100.4946) is installed. If it is and you rely on an affected drive, avoid heavy write workloads. (support.microsoft.com)
• 4.) Inspect vendor firmware and tools. Use your SSD vendor’s dashboard/utility to check firmware versions; apply only vendor‑recommended firmware updates — after backing up — because firmware can address controller bugs that interact with host changes. (borncity.com)
• 5.) If a drive disappears during a transfer: power down the system, document event timestamps and logs (Event Viewer), image the drive if the data is critical, and contact vendor support. Imaging immediately preserves forensic evidence and increases the chance of data recovery.
• 6.) Do not use the standalone wusa uninstall for the combined package: because this KB is shipped as a combined SSU + LCU, the LCU cannot be removed with wusa /uninstall. Microsoft documents using DISM /Remove‑Package for the LCU portion. Administrators who need to block the update should use Device Management tools (WSUS, SCCM, MDM) or pause updates per Microsoft’s guidance. (support.microsoft.com)

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Guidance for IT administrators and fleet managers​

• Stage the rollout. Pause broad deployment of KB5063878 across production fleets and test KB5063878 against representative hardware with large‑write workloads in a controlled environment. Community reports indicate this class of bug is workload-sensitive and can be caught by large‑write regression tests.
• Use update management tools. Leverage WSUS/SCCM (and Microsoft’s Known Issue Rollback mechanisms) to withhold or selectively distribute the update while investigations continue. There were earlier enterprise deployment regressions tied to this KB that required a re‑release for WSUS/SCCM channels, illustrating the need for controlled staging.
• Collect telemetry for vendor escalation. If a drive fails, collect logs, SMART dumps, vendor diagnostics, and an image if possible, then open tickets with the SSD vendor and Microsoft. Coordinated telemetry from vendor firmware and Microsoft kernel-level diagnostics will be necessary to reach a durable fix.

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How this gets fixed: realistic remediation pathways​

• Vendor firmware updates. If the root cause is a controller firmware edge case exposed by altered host behavior, vendors will need to release firmware updates to handle the changed timing/command sequences or to harden recovery paths. These updates will likely be the fastest path to a durable fix for affected drives. (igorslab.de)
• Microsoft mitigation or rollback. If the cause proves host-side (a storage stack regression), Microsoft can either publish a targeted mitigation (e.g., a change in how the OS issues long sequential writes or adjustments to HMB allocations) or reissue a corrected package for the affected component. Microsoft also has the Known Issue Rollback (KIR) tools to mitigate install/distribution regressions. (support.microsoft.com)
• Combined fix approach. It is plausible the final solution will be a combination of vendor firmware updates plus a Microsoft adjustment — the same cooperative remediation approach used in past 24H2 firmware/compatibility incidents.

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What to watch next​

• Microsoft Release Health and the KB5063878 support page for any new Known Issues entries or mitigations. (support.microsoft.com)
• Official advisories and firmware releases from SSD manufacturers for specific controller families (Phison statements, Kioxia, Corsair, WD/SanDisk). (borncity.com)
• Independent reproductions and technical write‑ups from storage specialists (Igor’s LAB, Guru3D) that provide reproducible test cases and device lists; these are useful for risk triage but are not a substitute for vendor confirmation. (igorslab.de) (guru3d.com)

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Strengths and weaknesses of the current evidence​

Notable strengths​

• Multiple independent testers and reputable enthusiast outlets reproduced a consistent symptom profile with similar trigger characteristics. That reproducibility strengthens the causal link to the update and reduces the probability of incidental hardware faults. (tomshardware.com) (guru3d.com)
• The failure fingerprint (controller invisibility, unreadable SMART, corruption of files written during the window) points to a controller-level event rather than a simple OS UI glitch; such a signature is technically meaningful for root-cause hypotheses. (igorslab.de)

Key uncertainties and risks​

• Microsoft had not, at the early reporting stage, added a storage-related “known issue” entry for KB5063878. That absence leaves some open questions about how widespread the company believes the problem to be and whether an official mitigative action is imminent. (support.microsoft.com)
• Community-sourced device lists are valuable but incomplete. They cannot substitute for vendor and Microsoft telemetry; not every drive with a named controller is affected, and not every affected drive behaves identically, which complicates mass communication and remediation. (notebookcheck.net)
• There is a real risk of data loss for users who continue to perform large transfers on potentially affected hardware. Post‑incident recovery varies and may sometimes require RMA or reformatting that destroys user data if not imaged first.

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Recommendations — concise checklist​

• Back up critical files to external or cloud storage now. (notebookcheck.net)
• Avoid large sequential writes to NVMe drives until firmware or Microsoft guidance is available. (guru3d.com)
• Check firmware and vendor utilities; apply vendor-recommended firmware updates only after backing up. (borncity.com)
• If a drive fails during a transfer: power off, image the drive if the data is valuable, and collect logs for vendor/Microsoft support.
• Admins: stage KB5063878 and hold deployment for machines with susceptible drives; use WSUS/SCCM controls and monitor Microsoft Release Health.

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Conclusion​

The KB5063878 episode is an unsettling reminder that even routine cumulative updates can interact with complex device firmware in unexpected ways. Independent reproductions by enthusiasts and specialist outlets show a technically coherent failure mode: sustained large writes can cause certain SSDs to stop responding and, in some cases, leave behind corrupted data. The evidence so far is sufficient to warrant immediate, conservative action — back up data, avoid mass writes on vulnerable drives, and pause broad deployment in managed environments — while leaving open the need for vendor and Microsoft telemetry to deliver a definitive fix.
Community reporting has exposed a reproducible and consequential class of storage regressions; the responsible response is rapid, coordinated remediation rather than alarm-driven panic. Prior incidents show that firmware updates and targeted OS mitigations can and do resolve these interactions when manufacturers and platform providers cooperate. For now, preserve data, exercise caution with large file operations, and watch Microsoft and SSD vendors for official advisories and tested firmware releases. (support.microsoft.com) (igorslab.de)

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Source: bgr.com Microsoft's Latest Windows 11 Update Is Reportedly 'Killing' Some SSDs - BGR

 

[ChatGPT]

Microsoft’s August cumulative for Windows 11 (KB5063878) has been implicated in a narrow but serious storage regression: under sustained, large sequential writes some solid‑state drives can stop responding, vanish from Windows, and in a subset of reports leave files or partitions corrupted or inaccessible. (support.microsoft.com)

Background / Overview​

Microsoft released KB5063878 (OS Build 26100.4946) on August 12, 2025 as the combined servicing‑stack and cumulative quality update for Windows 11, version 24H2. The official release notes list security and quality fixes and initially state that Microsoft is “not currently aware of any issues with this update.” (support.microsoft.com)
Within days of the rollout, independent testers and multiple specialist outlets reproduced a consistent failure profile: during sustained, large sequential writes (community tests commonly converge around ~50 GB or more), certain NVMe SSDs may become unresponsive, disappear from File Explorer / Device Manager, and present unreadable SMART/controller telemetry. Reboots sometimes restore temporary visibility, but data written during the incident window can be corrupted or lost. (tomshardware.com, guru3d.com)
This story is evolving rapidly. Community reproductions, vendor acknowledgements, and official Microsoft messaging have been moving in parallel; the best evidence right now comes from methodical hobbyist testing and multiple independent tech outlets validating those tests. Treat community-sourced model lists and early vendor comments as investigative leads pending full forensic disclosure.

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What users are reporting​

Symptom profile (what actually happens)​

• A large sequential write—for example, a game update, archive extraction, cloning operation, or mass file copy—proceeds normally and then abruptly fails after tens of gigabytes (commonly around 50 GB).
• The target SSD may disappear from File Explorer, Disk Management, and Device Manager while the write is in progress.
• Vendor utilities and SMART telemetry may no longer be readable; the drive can appear to have been removed from the system topology.
• Rebooting sometimes restores the drive, but files being written at the time of failure are often incomplete or corrupted; in a small number of reports the drive remained inaccessible without vendor intervention. (guru3d.com, wccftech.com)

Typical trigger and workload​

Multiple community reproductions converge on the same trigger profile: sustained, large sequential writes (often cited near or above ~50 GB) on drives that are not empty and may already be moderately utilized (many reports note >50–60% fill). Real‑world triggers are realistic: large game installs, moving big libraries, cloning tools and backup jobs. The pattern is repeatable in some setups, which makes it a pressing operational signal rather than a one‑off anecdote.

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Which drives and controllers appear affected​

Early collations and independent tests show clustering rather than universality: certain controller families and firmware revisions are disproportionately represented in repros, with Phison‑based drives frequently mentioned. Phison itself has acknowledged that it is investigating possible effects from KB5063878 (and related updates) and is working with partners to identify impacted controllers. (tomshardware.com, windowsforum.com)
Community‑compiled model examples that have surfaced in coverage and test logs include:

• Corsair Force MP600 (Phison PS5012‑E12 variants reported in community lists). (wccftech.com)
• KIOXIA Exceria Plus G4. (wccftech.com)
• Fikwot FN955. (wccftech.com)
• SanDisk Extreme PRO M.2 NVMe 3D SSD. (wccftech.com)

Important caveats: not all drives of the same model or with the same controller fail in every configuration. Firmware revision, drive capacity, whether the drive is DRAM‑less or uses Host Memory Buffer (HMB), the motherboard/BIOS, and even specific storage drivers can change the outcome. Community lists are investigative leads—use them to triage and test, not as absolute blacklists.

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What the evidence suggests — plausible technical mechanisms​

Several plausible, non‑mutually exclusive mechanisms recur in expert write‑ups and community posts:

• Host Memory Buffer (HMB) allocation behavior: DRAM‑less drives that rely on HMB are sensitive to host allocation changes. Prior Windows 11 interactions exposed HMB timing issues in some drives; a subtle change in host behavior can push a controller into an unhandled edge case.
• Kernel/storage stack regression: a regression in how Windows buffers or sequences NVMe commands during sustained sequential I/O could alter timing or buffer pressure in ways that expose latent firmware bugs. This would show up as controller stalls rather than ordinary driver crashes. (guru3d.com)
• Controller firmware lock‑ups under sustained stress: prolonged large writes stress the NAND management, mapping-table updates, wear‑leveling and garbage‑collection behaviors inside the controller. If firmware has a race condition or unhandled exception under that stress, the controller can become unresponsive and appear "removed" at the host level.

Taken together, the fingerprint—drive disappearance during long continuous writes, unreadable SMART, and occasional unrecoverable state—reads like a controller or firmware hang exposed by a host‑side behavior change. Full root‑cause attribution will require vendor and Microsoft telemetry. Until then, the hypothesis that KB5063878 introduced or exposed a timing/behavior change in the Windows storage stack remains the most coherent explanation.

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How Microsoft and vendors have responded​

• Microsoft’s KB entry for KB5063878 lists the update and its build (26100.4946) and did not initially list a storage‑device failure as a known issue; the KB page still contains the standard release material and instructions for uninstalling the LCU component using DISM where appropriate. (support.microsoft.com)
• Phison issued a statement acknowledging it had been “recently made aware of the industry‑wide effects” associated with KB5063878 and KB5062660 and said it is reviewing affected controllers and working with partners to provide advisories and remediation as needed. (tomshardware.com, pcgamer.com)
• SSD vendors and system OEMs have been monitoring community reports. In prior incidents the typical remediation paths included targeted firmware updates from SSD vendors, Microsoft mitigations such as Known Issue Rollbacks (KIR) for enterprise channels, or both. At the time of reporting, firmware fixes and full diagnostics were still being coordinated.

Important: vendor and Microsoft messaging has generally been measured — acknowledging investigation without assigning definitive blame. That restraint is appropriate given the variables (firmware revisions, SKUs, host platforms). However, Phison’s public acknowledgement is a significant escalation compared with purely community‑sourced troubleshooting. (tomshardware.com)

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Scope and prevalence — how widespread is this?​

So far the incident appears targeted rather than universal. Reports are technically consistent and reproducible in lab settings, but they remain limited compared with the total install base of Windows 11 and NVMe SSDs. That said, even a small failure rate is consequential because the observable result can be complete data loss on an affected drive. Multiple specialist publications and community test benches reproduced the behavior, which elevated the issue beyond isolated anecdotes. (guru3d.com, wccftech.com)
The risk profile looks like this:

• Probability: low-to-moderate in the general population (not every user or drive), but higher for specific controller/firmware combos and for systems performing sustained large writes.
• Impact: high for affected users — potential for inaccessible partitions and corrupted files.
• Detectability: moderate — the failure is obvious when it happens (drive disappears), but data loss may not be noticed until later.

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Immediate, practical guidance for Windows users​

If you have already installed KB5063878 and use NVMe SSDs (especially drives with Phison controllers or the community‑listed models), take these defensive steps now:

• Back up critical data immediately to a second physical disk or reliable cloud storage. Do not rely on the at‑risk drive for primary backups.
• Avoid sustained large sequential writes until the issue is resolved. This includes:
• Large game downloads or updates
• Mass file copies and cloning operations
• Long media exports or backup jobs targeted at the suspect SSD
• Check your SSD vendor’s support utility (Corsair iCUE, SanDisk Dashboard, Kioxia/Crucial tools) for firmware advisories and apply firmware updates only after backing up. Firmware updates may be the ultimate fix for controller‑level bugs. (wccftech.com, guru3d.com)
• For enterprise environments, stage KB5063878 in a test ring and validate large‑write workloads before broad deployment; consider using Microsoft’s servicing controls (Known Issue Rollback) or deferring the patch for vulnerable fleets. Error 0x80240069 was also reported in managed deployment paths and prompted Microsoft servicing mitigations.
• If a drive becomes inaccessible mid‑write, stop further write attempts and capture system logs (Event Viewer, NVMe events) and vendor diagnostic output. Create a forensic image of the device before reformatting or running destructive repair steps—imaging preserves the chance of vendor recovery and RMA support.

These actions trade a small amount of convenience for a meaningful reduction in the risk of permanent data loss.

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If a drive disappears mid‑write — recommended recovery steps​

• Do not initialize or reformat the disk. That can overwrite partition metadata and reduce the chance of successful recovery.
• Attempt safe reboots only once; repeated reboot/write cycles increase risk.
• Run vendor diagnostic tools (the same utility used for firmware updates) to query SMART and controller state. Note that many reports show those utilities returning unreadable or error states after the fault. (guru3d.com)
• If the drive remains inaccessible, create a block‑level forensic image using read‑only tools (for example, dd‑based imaging from a Linux live environment or a hardware imager) and share that image with vendor support or a professional data‑recovery service when requested. Document steps taken and capture system logs for RMA/diagnostics.
• Engage vendor support and provide reproduction logs, firmware revision, motherboard/BIOS version and workload details. Vendors will often request images and logs before accepting RMA claims tied to firmware/controller behavior.

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Guidance for IT administrators and system builders​

• Immediately prioritize backups and snapshots for production systems that received KB5063878.
• Put affected systems into a test ring and run representative sequential write workloads (50 GB+ sustained) against sample hardware that matches production inventory.
• Use Microsoft’s deployment controls to pause or rollback the update on managed channels where risk is unacceptable; consult the Microsoft servicing documentation for Known Issue Rollback procedures and the company’s guidance on removing the LCU with DISM. (support.microsoft.com)
• Treat vendor utilities and firmware updates as a first‑class mitigation. Coordinate with SSD vendors and platform OEMs to receive validated firmware and testing guidance. Phison has publicly committed to partner advisories, which means vendor firmware is the likely distribution channel for a permanent fix. (tomshardware.com)

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Strengths and limitations of the current evidence​

Strengths​

• Independent reproducibility: multiple hobbyist researchers and specialist outlets reproduced an identical symptom fingerprint under similar workloads, increasing confidence that the issue is real and not a single faulty drive.
• Vendor acknowledgement: Phison publicly acknowledged the reports and said it is investigating, which elevates the issue from isolated community noise to an industry‑level incident. (tomshardware.com)
• Technical plausibility: the failure profile (controller hang during extended writes) matches known failure modes when host/driver behavior interacts badly with firmware, especially on DRAM‑less or HMB‑reliant drives.

Limitations and open questions​

• Lack of a definitive, single‑point root cause: at time of reporting neither Microsoft nor SSD vendors published a fully detailed forensic root‑cause analysis tying KB5063878 to a specific kernel regression, driver change, or firmware bug. Until vendor telemetries and Microsoft diagnostics are published, root cause remains a well‑supported hypothesis rather than a proven fact.
• Incomplete model list: community‑compiled lists are useful for triage but are not exhaustive or authoritative; firmware revisions and OEM configuration materially change risk. Treat such lists as starting points, not final guidance.
• Potential confounders: motherboard firmware, PCIe link behavior, and thermal throttling can mask or amplify the issue; multiple independent variables make reproducibility outside of carefully controlled test benches harder to generalize.

Any advisory that claims “only Phison controllers are affected” should be treated with caution until vendors publish exhaustive telemetry; the most defensible stance is that some Phison‑equipped drives appear over‑represented in reports, but other controllers have also surfaced in isolated test rigs. (guru3d.com, wccftech.com)

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What to watch for next​

• Vendor firmware advisories and utilities that publish targeted fixes or firmware rollouts for specific controller/factory SKUs.
• Microsoft release‑health updates or an explicit Known Issue entry that acknowledges storage regressions and provides mitigation or rollback guidance.
• Wider independent verification from large test labs and replication across motherboard, BIOS and CPU platforms; that will clarify whether this is strictly a controller/firmware issue or a host/OS timing regression that interacts with specific controller families.

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Conclusion​

KB5063878 has surfaced as a credible, actionable risk for a small but significant class of storage configurations: sustained large sequential writes can trigger controller stalls that make drives disappear and, in some cases, cause data loss. The early evidence combines repeatable community test cases, specialist outlet reproductions, and a vendor acknowledgement from Phison—together creating enough urgency for a pragmatic defensive posture: back up, avoid heavy writes on recently patched systems, stage the update in test rings, and apply vendor‑issued firmware updates only after backing up critical data.
This incident reinforces a perennial lesson: modern NVMe SSD reliability depends on a fragile choreography between firmware, host drivers, and OS behavior. When that dance is disrupted—even by an otherwise routine security rollup—the consequences can be immediate and irreversible for affected users. Prioritize data protection and coordinate with vendors and Microsoft for the authoritative troubleshooting and remediation steps as they become available.

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Source: Ubergizmo Windows 11 Update KB5063878 Reportedly Causing SSD Failures