Microsoft’s latest public update on the mid‑August patch storm is straightforward: after investigation, the company says the August 2025 cumulative rollup did not cause a widespread failure mode that “breaks” SSDs, but the episode still exposes fragile cross‑stack dependencies and persistent risks for users who handle large, heavy I/O work on diverse storage hardware.
The Windows servicing wave on August 12, 2025 delivered the combined Servicing Stack Update (SSU) plus Latest Cumulative Update tracked by the community as KB5063878 for Windows 11 version 24H2 (OS Build 26100.4946). Within days, hobbyist testers and professional outlets published reproducible test recipes showing a clear operational fingerprint: during sustained large sequential writes (commonly reported around the tens‑of‑gigabytes mark), some NVMe drives would become unresponsive, disappear from the operating system, and in a minority of reports return with corrupted or inaccessible files after reboot.
That community reporting prompted Microsoft to open an investigation and work with storage partners. Controller vendor Phison completed lab validation and published a test summary saying it dedicated substantial lab hours and test cycles to the reported drives and could not reproduce a universal failure, while Microsoft’s internal testing and telemetry similarly reported no platform‑wide increase in disk failures tied to the update. Despite those vendor statements, a small but alarming set of field reports remains, and several practical mitigations have been circulated to reduce immediate risk.
SSD controller vendor Phison published a lab validation summary that reported hundreds to thousands of cumulative test hours across many cycles on drives that were claimed to be impacted. Phison said its lab campaign was unable to reproduce the reported failures and that no partners or customers had reported similar RMA spikes during their testing window.
Both positions—Microsoft’s telemetry and Phison’s lab work—are important and encourage measured response, but they do not close the investigation for two reasons:
The responsible posture for users, prosumers and administrators is unchanged: back up critical data immediately, stage updates until representative hardware has been validated under realistic workloads, avoid heavy sequential writes on freshly patched machines, and follow vendor guidance for firmware updates and diagnostics. Vendors and Microsoft must continue to collaborate openly, publish detailed forensic findings when available, and provide reproducible mitigations so that both the rare edge cases and the common flows remain safe for everyone.
Source: Neowin Microsoft: No, Windows 11 update did not break your SSD
Background / Overview
The Windows servicing wave on August 12, 2025 delivered the combined Servicing Stack Update (SSU) plus Latest Cumulative Update tracked by the community as KB5063878 for Windows 11 version 24H2 (OS Build 26100.4946). Within days, hobbyist testers and professional outlets published reproducible test recipes showing a clear operational fingerprint: during sustained large sequential writes (commonly reported around the tens‑of‑gigabytes mark), some NVMe drives would become unresponsive, disappear from the operating system, and in a minority of reports return with corrupted or inaccessible files after reboot.That community reporting prompted Microsoft to open an investigation and work with storage partners. Controller vendor Phison completed lab validation and published a test summary saying it dedicated substantial lab hours and test cycles to the reported drives and could not reproduce a universal failure, while Microsoft’s internal testing and telemetry similarly reported no platform‑wide increase in disk failures tied to the update. Despite those vendor statements, a small but alarming set of field reports remains, and several practical mitigations have been circulated to reduce immediate risk.
What happened — the symptom profile explained
Independent test benches and community reproductions converged on a repeatable failure pattern that made the incident credible and urgent.- Symptom: an NVMe SSD that is targeted by a large, sustained write operation simply stops responding to the OS. It may disappear from File Explorer, Disk Management and Device Manager. SMART and vendor utility telemetry can become unreadable or return errors.
- Typical trigger profile reported by testers: sustained sequential writes on the order of tens of gigabytes (commonly cited ~50 GB), usually to drives that were already partially used (often reported as >50–60% full).
- Outcome variability: many affected drives returned to service after a reboot with little or no permanent damage; a minority remained inaccessible and required vendor tools, firmware reflash, imaging or RMA-level recovery. A few user reports claim severe data loss on multi‑terabyte drives.
- Affected hardware patterns: early reports disproportionately showed drives built on Phison controller families — including some DRAM‑less designs that rely on NVMe Host Memory Buffer (HMB) — but other controller families and models also appeared in isolated incidents.
Microsoft and vendor responses
Microsoft’s public posture over the last week has followed a clear sequence: acknowledge reports, attempt internal reproduction, engage partners, solicit affected user telemetry, and publish service guidance while monitoring for further evidence. The company’s stated position is that its internal testing and telemetry have not shown a platform‑wide spike in disk failures or file corruption tied to KB5063878, and that it has found no confirmed link between the security update and the kinds of hard‑drive failures reported on social media.SSD controller vendor Phison published a lab validation summary that reported hundreds to thousands of cumulative test hours across many cycles on drives that were claimed to be impacted. Phison said its lab campaign was unable to reproduce the reported failures and that no partners or customers had reported similar RMA spikes during their testing window.
Both positions—Microsoft’s telemetry and Phison’s lab work—are important and encourage measured response, but they do not close the investigation for two reasons:
- Telemetry and lab matrices have limits. Telemetry looks for statistically significant increases across millions of devices; rare edge cases in specific configurations may not surface as a telemetry spike. Lab matrices can miss particular combinations of motherboard firmware, BIOS settings, chipset drivers, thermal state, and workload timing that exist in the field.
- Anecdotal reproducibility at the hands of credible testers remains a signal. Multiple independent test benches published repeatable recipes that triggered drive disappearance under consistent conditions; these hands‑on reproducible results cannot be dismissed outright.
Technical hypotheses: why an OS update can expose a controller bug
Storage subsystems are co‑engineered systems: the OS storage stack, NVMe driver, chipset/PCIe root complex, firmware on the SSD controller, NAND management code, and even thermal/power management interact in tight timing windows. Several plausible mechanisms explain why a seemingly unrelated OS patch could make a drive hang under heavy sequential writes:- Host Memory Buffer (HMB) timing and allocation: DRAM‑less controllers rely on HMB to offload some metadata and caching to host RAM. Changes in how Windows allocates or schedules HMB usage, or different timings for buffer flushes, can expose firmware races that previously went unnoticed.
- OS‑level I/O scheduling and buffered write behaviour: updates that modify kernel I/O scheduling, buffered writes, or caching/flush semantics could cause controller timeouts when added latency or ordering differences occur during heavy sustained transfers.
- Controller firmware edge cases: some firmware has implicit assumptions about host behavior (timing windows, queue depths, or error handling). If the host deviates just enough during extreme workloads, the controller may enter a non‑recoverable hang state.
- Thermal and power envelopes: sustained large writes generate heat; combined with higher NAND/programming activity on a partially full drive, thermal throttling can create timing anomalies or trigger conservative fixes in firmware that leave the controller unresponsive.
- Memory leaks or OS buffering faults: community test reports suggested situations involving hibernation or very large hiberfil.sys allocations may have contributed to specific RAW conversion incidents on large HDDs; similar host memory anomalies could affect SSD behavior under stress.
- BIOS/chipset/driver interplay: motherboard BIOS versions, platform-specific SATA/NVMe controller drivers, and chipset firmware can create unique host environments that differ from vendor test labs.
What we know (verified points)
- KB5063878 was released as part of the August 12, 2025 servicing wave for Windows 11 24H2.
- Community testers reproduced a failure fingerprint: drives disappearing under sustained large sequential writes on partially full NVMe media.
- Microsoft investigated and reported no telemetry‑driven increase in disk failures and asked affected users to submit precise diagnostics.
- Phison reported large internal testing totals (multiple thousands of cumulative hours and thousands of cycles) and stated it could not reproduce the issue in its labs.
What remains uncertain or unverifiable right now
- The exact cause for every reported field incident. Many individual user reports differ in hardware, firmware revision, and workload, so a single universal root cause has not been published.
- Whether specific reports of permanent controller damage or irrecoverable bricking are directly attributable to the KB update, firmware bugs alone, or preexisting drive health issues. Some user accounts describe catastrophic data loss on large HDDs or SSDs; those remain subject to vendor forensics and are not yet consolidated into a broad, verified failure signal.
- The definitive test matrix and logs behind vendor lab claims. Vendor statements about testing hours and cycles are credible but not third‑party audited in public; they are company disclosures that help understanding but do not substitute for independent forensic publication.
- Whether a targeted firmware update, a Windows hotfix, or both will be the long‑term remedy for every configuration. In past incidents, solutions have come as coordinated firmware updates plus host mitigations.
Practical guidance for users (short‑term risk reduction)
If you run Windows 11 and rely on local NVMe or HDD storage for critical data, follow these conservative, practical steps now:- Back up critical data immediately. Use the 3‑2‑1 rule where possible (three copies, two different media types, one offsite).
- If you have not installed KB5063878 and your daily work involves large sustained writes (game installs, mass archive extraction, cloning, large video exports), consider pausing or staging the update until vendor guidance is available for your SSD model.
- If you already installed the update, avoid heavy sequential writes on systems with drives that match model/firmware patterns seen in community reproductions. Break large transfers into smaller batches.
- Keep SSD firmware and vendor utilities up to date. Check the OEM/Vendor support pages and apply firmware updates only after backing up data. Firmware flashes carry risk—never flash without a backup.
- If a drive disappears during a write:
- Stop further write activity immediately.
- Do not repeatedly reboot blindly; capture logs if you can.
- Use vendor tools to collect SMART and controller logs.
- Image the drive for recovery attempts and vendor forensics before reformatting.
- If you’re in an enterprise:
- Stage KB deployment in a test ring that represents production hardware, including storage, before mass rollout.
- Inventory endpoints for potentially affected models and pause broad deployment where necessary.
- Use WSUS, SCCM, or MDM controls to withhold updates while you run workload tests.
For power users and technicians: investigative checklist
- Reproduce carefully: use controlled test rigs with identical firmware/BIOs/drivers and the same sustained sequential write workload to check for reproductions.
- Capture full logs: enable verbose disk and kernel tracing (Event Tracing for Windows, Windows Performance Recorder), collect vendor tool dumps and SMART logs, and snapshot machine firmware versions and driver versions.
- Image before repair: if a drive becomes inaccessible, create a forensic image and hand it to the vendor or a qualified data recovery service before attempts to reformat or reflash the drive.
- Validate firmware: confirm exact firmware string and test after upgrade in a safe environment. Keep records of which firmware revisions were tested.
- Consider thermal mitigation: for high‑performance NVMe modules, heatsinks or proper airflow reduce thermal variables and may prevent thermal‑state‑dependent anomalies.
Critical analysis — strengths and weaknesses of the current narrative
Strengths- Rapid community reproducibility: independent testers produced repeatable failure recipes quickly, which focused vendor and Microsoft investigation on a credible workload window.
- Vendor engagement: Phison and other suppliers engaged swiftly and ran validation work, reducing the risk of unchecked blame and enabling data‑driven triage.
- Microsoft telemetry and formal channels: Microsoft’s use of telemetry and the Feedback Hub helps contain noise and prioritize instrumentation for real incidents.
- Lab non‑reproducibility is not exoneration. A failure pattern that depends on a narrow set of timing and thermal conditions may be missed by even extensive lab tests that do not exactly replicate a field platform.
- Telemetry blindness to rare but severe edge cases. Telemetry aggregates signal across millions of devices and can miss small‑population, high‑impact issues that nonetheless destroy data for individual customers.
- Communication noise: overlapping issues—install errors affecting WSUS/SCCM, streaming regressions affecting NDI/OBS, and storage disappearance stories—create confusion for users and administrators trying to triage which KB applies to which symptom.
- The data‑loss dimension: storage failures that truncate or corrupt data during writes are the most serious kind of regression. Even if a small percentage of drives are affected, the cost to users with critical local data can be catastrophic.
Longer‑term implications for Windows servicing and SSD vendors
- Pre‑release testing needs more representative coverage. The sheer diversity of SSD controllers, firmware versions and OEM combinations argues for larger, more representative stress suites in pre‑release validation, including heavy sequential write loops to partially full drives in thermal chambers and a variety of BIOS/driver states.
- Better diagnostic telemetry and logging hooks. Vendors and Microsoft should collaborate on richer, privacy‑respecting traces that can capture controller hang fingerprints without flooding telemetry pipelines. That includes clearer signals when a device disappears from the OS stack mid‑IO.
- Faster coordinated mitigation paths. Past incidents show that the healthiest path is a coordinated firmware rollout plus, if necessary, a host‑side mitigation or KB block until firmware is applied. Microsoft has used blocks or staged rollouts before; refining that process for storage edge cases would shorten remediation cycles.
- End‑user education: maintain backups, stage updates, and split large transfers during the post‑patch window. That risk management posture should be standard practice for prosumers and IT teams alike.
Recommended immediate actions for administrators and vendors
- Administrators: withhold KB5063878 broadly until representative fleets have been stress‑tested; use pilot rings that include storage hardware diversity and heavy I/O tests.
- Vendors: publish precise affected‑model lists with firmware versions and reproducible test recipes; where firmware fixes are required, provide clear firmware upgrade instructions and version‑to‑version delta notes.
- Microsoft: continue to collect detailed support cases and publish known issue guidance where appropriate. If a targeted remediation (host fix, driver update, or telemetry change) is identified, publish a clear KB article and, if needed, roll back the update for affected configuration fingerprints.
Conclusion
The short answer to the panic headline is: Microsoft and a major controller vendor report no evidence of a broad, update‑driven mass “bricking” of SSDs after the August 2025 Windows patch, and their lab and telemetry checks so far provide reassurance that this is not a universal fault. The longer, more important takeaway is that even with sophisticated telemetry and large lab campaigns, the modern storage stack remains fragile at the edges. Rare but severe failure modes—triggered by a precise blend of firmware, host drivers, platform firmware, thermal conditions and workload patterns—can still occur.The responsible posture for users, prosumers and administrators is unchanged: back up critical data immediately, stage updates until representative hardware has been validated under realistic workloads, avoid heavy sequential writes on freshly patched machines, and follow vendor guidance for firmware updates and diagnostics. Vendors and Microsoft must continue to collaborate openly, publish detailed forensic findings when available, and provide reproducible mitigations so that both the rare edge cases and the common flows remain safe for everyone.
Source: Neowin Microsoft: No, Windows 11 update did not break your SSD