Windows 11’s 25H2 enablement package is currently triggering targeted upgrade blocks for systems using certain Western Digital and SanDisk NVMe SSDs — a conservative compatibility hold that echoes the same Host Memory Buffer (HMB) firmware problems first seen during the 24H2 rollout. Users who attempt an in-place switch from 24H2 to 25H2 on affected drives may see Windows Update refuse the enablement package until drive firmware is updated, and vendors strongly recommend installing the latest SSD firmware before proceeding.
Microsoft’s modern feature-update process uses staged rollouts and targeted compatibility holds to prevent known problematic hardware or driver combinations from receiving feature updates. That safeguard system is designed to reduce the blast radius of regressions that could otherwise cause system instability or data loss. The recent 25H2 enablement package is rolling out to machines already on 24H2, but Microsoft will withhold the enablement flag for devices that match known risky configurations until vendors ship validated fixes or mitigations.
The current block affecting some WD and SanDisk NVMe SSDs is not a brand-new root cause; it traces back to an earlier interaction between Windows 11 24H2 (and associated cumulative updates) and the Host Memory Buffer functionality used by DRAM-less SSDs. That earlier incident produced Blue Screens of Death (BSODs) and data‑at‑risk scenarios for a subset of drives, prompting vendor firmware pushes and Microsoft compatibility safeguards. The 25H2 hold appears to be a continuing, precautionary measure while the ecosystem stabilizes.
At the same time, the episode underscores larger systemic tensions: modern operating systems continuously evolve their low-level behaviors, and commodity storage firmware must be validated against those changes across many SKUs. The responsible path for users and IT teams is straightforward — prioritize firmware hygiene, respect upgrade holds, and adopt cautious pilot deployments — while recognizing that sensational narratives about widespread, irreversible bricking rarely survive rigorous vendor and lab testing.
For Windows users with WD/SanDisk NVMe drives, the recommendation is clear and simple: update SSD firmware through the official vendor dashboard, back up important files, and let Microsoft deliver 25H2 only after the compatibility hold clears for your device. That combination minimizes the chance of encountering a preventable failure and preserves a smooth upgrade experience.
Source: Пепелац Ньюс https://pepelac.news/en/posts/id4422-windows-11-25h2-blocks-upgrade-on-wd-sandisk-nvme-ssds/
Background
Microsoft’s modern feature-update process uses staged rollouts and targeted compatibility holds to prevent known problematic hardware or driver combinations from receiving feature updates. That safeguard system is designed to reduce the blast radius of regressions that could otherwise cause system instability or data loss. The recent 25H2 enablement package is rolling out to machines already on 24H2, but Microsoft will withhold the enablement flag for devices that match known risky configurations until vendors ship validated fixes or mitigations.The current block affecting some WD and SanDisk NVMe SSDs is not a brand-new root cause; it traces back to an earlier interaction between Windows 11 24H2 (and associated cumulative updates) and the Host Memory Buffer functionality used by DRAM-less SSDs. That earlier incident produced Blue Screens of Death (BSODs) and data‑at‑risk scenarios for a subset of drives, prompting vendor firmware pushes and Microsoft compatibility safeguards. The 25H2 hold appears to be a continuing, precautionary measure while the ecosystem stabilizes.
What exactly is being blocked and why
The technical focal point: Host Memory Buffer (HMB)
HMB is an NVMe feature that lets DRAM-less SSDs borrow a portion of system RAM for caching and mapping tasks. It improves performance and cost-efficiency for drives without onboard DRAM, but it introduces a dependency on host memory allocation semantics. When an OS or driver changes the way HMB is requested, sized, or released, firmware that expects previous behavior can mis-handle those requests — with consequences ranging from performance quirks to kernel crashes. The reported cases involve HMB allocation/management differences that, in some firmware builds, can lead to critical errors under specific workloads.The upgrade block mechanism
When Microsoft detects telemetry or vendor advisories that a particular device/driver combination will likely fail during or after a feature update, it can place a targeted “safeguard hold.” This prevents Windows Update from offering the feature update to devices matching the signature until the hold is cleared. For affected WD and SanDisk drives, that hold remains in place until firmware is updated and telemetry shows the failure rate has subsided. The aim is to prevent users from upgrading and encountering an immediate, avoidable crash or worse, data corruption.Affected devices and vendor response
Multiple vendor support entries and reputable coverage list the specific 2TB models that were implicated during the 24H2 episode and that continue to be mentioned in 25H2 compatibility advisories. The models repeatedly identified include:- WD_BLACK SN770 NVMe SSD — 2TB variants.
- WD_BLACK SN770M NVMe SSD — 2TB variants.
- WD Blue SN580 NVMe SSD — 2TB variants.
- WD Blue SN5000 NVMe SSD — 2TB variants.
- SanDisk Extreme M.2 NVMe SSD — 2TB variants.
What happened in 24H2 — short chronology
- After the Windows 11 24H2 servicing stream reached broad distribution, reports surfaced of BSODs and systems losing access to certain NVMe drives during heavy write activity. Community testers reproduced scenarios where drives would disappear from the OS under sustained writes on drives that were moderately used.
- Initial hypotheses pointed to host-side changes in memory allocation (HMB) as the trigger; vendors and Microsoft launched investigations. Vendor firmware updates and temporary registry workarounds (disabling HMB allocation) were circulated as stopgaps.
- Western Digital and SanDisk issued firmware updates targeted at the affected models and advised customers to update firmware before upgrading to 24H2. Microsoft used targeted holds to prevent further automatic upgrades for affected configurations.
- Independent vendor and controller-maker (Phison) testing later attempted to reproduce widespread bricking claims and publicly reported no systemic failures after extensive testing, a nuance that complicates how broadly the original incident should be interpreted.
How to check whether your PC is affected
- Open Device Manager → Disk Drives and note the NVMe model string. If you have a WD or SanDisk NVMe drive listed above, take extra caution.
- Use vendor tools (Western Digital Dashboard or SanDisk Dashboard) to read the firmware version; the dashboards will usually flag available firmware updates. Vendors published updated firmware IDs in their support articles.
- Check Windows Update: if the 25H2 enablement package does not appear despite being on 24H2, a targeted safeguard may be in effect. Microsoft’s rollout can take time; if you have an affected drive, expect the upgrade offer to be delayed until the firmware update is applied or the block is cleared.
Practical guidance: safe upgrade path
Follow a conservative, stepwise approach to minimize risk:- Back up all important data to external storage or cloud before touching firmware or OS upgrades. Firmware updates and feature upgrades carry non-zero data risk.
- Use the vendor’s official dashboard to check for and apply firmware updates to your SSD. The dashboard typically shows “Firmware Update Available” if a newer build exists. Follow the vendor instructions — many firmware flashes include a shutdown step that writes the firmware during power cycle.
- After flashing firmware, reboot and let the vendor tool validate the drive health. If the dashboard reports success, give Windows Update some time (up to 48 hours in some reported cases) for the compatibility hold to lift and the feature update offer to propagate.
- Do not bypass Microsoft’s safeguards by forcing an upgrade with Media Creation Tool or community tools unless you fully understand and accept the risk; bypassing a safeguard defeats the very protection designed to save you from catastrophic failure during or after upgrade.
Analysis: strengths, gaps, and risks
What's handled well
- Timely vendor firmware publishing. Western Digital and SanDisk responded by publishing HMB-focused firmware updates and dashboard tools to flash affected drives. That fast vendor action reduces the exposure window for vulnerable systems.
- Microsoft’s safeguard system performed as designed. The targeted hold prevented many users from receiving an update that had a known failure mode on certain hardware. Blocking a feature update for devices that match an identified risk profile is a blunt but effective way of minimizing impact.
- Clear remediation guidance. Vendor documents and reputable press outlets provided step-by-step firmware update guidance and registry-based mitigation steps for advanced users.
Open questions and limitations
- Root-cause clarity remains partial. While HMB allocation behavior is the plausible host‑side lever involved, complete forensic root-cause analysis tying a specific Windows commit to a single firmware bug has not been published in a single, vendor-verified report. Some public claims of “bricking” or mass failures were later questioned by Phison’s testing. Where multiple parties investigate a complex host‑controller interaction, full forensic disclosure often lags practical mitigation. Flag: treat broad-bricking claims with caution unless supported by vendor or Microsoft forensic artifacts.
- Firmware rollout fragility. Not all drive SKUs and capacity revisions share the same firmware — vendors must validate and publish builds for multiple part numbers. That complicates a single “update and done” narrative for consumers and enterprises with mixed inventories.
- User behavior risk. Some users may be tempted to bypass Microsoft’s safeguards and force an upgrade. That action removes the protection and could re-expose a system to the exact failure the hold intended to avoid. Enterprises, in particular, must weigh the trade-off between speed and safety.
Enterprise considerations
- Pilot before broad rollouts. Validate the 25H2 enablement package and vendor firmware combinations on representative hardware before mass deployment, especially on imaging or content-critical machines. Use staged rings and telemetry to watch for regressions.
- Lock down upgrade policies. Use Windows Update for Business, WSUS or WSIM to control when individual machines receive 25H2 and to ensure you do not inadvertently upgrade a device still pending a firmware flash.
- Prepare known-issue rollback (KIR) strategies. Microsoft will sometimes publish Known Issue Rollback artifacts or targeted mitigations; ensure your management tooling can apply or enforce KIR where needed.
Community testing, controller vendors, and the reputational angle
The incident spawned rigorous community testing and lively public debate. Some community tests suggested particular Phison-controller drives were vulnerable under certain high-write conditions, which stoked alarmist headlines about drives being “bricked” en masse. Phison, the SSD controller maker implicated by some reports, performed thousands of hours of testing and publicly stated it could not reproduce mass failures and found no evidence of systemic controller defects tied to the update. That contrast — community reproducibility vs. vendor testing — highlights how complex storage regressions can be and how careful labs must be in reproducing real-world conditions. Readers should treat early test anecdotes as useful signals but not definitive proof without cross-vendor forensic confirmation.What to watch next
- Vendor support pages and dashboards for firmware updates and explicit firmware version IDs. These remain the authoritative artifacts for whether your SKU is covered.
- Microsoft’s Windows Release Health and rollout notices for any updated entries about 25H2 safeguard lifts, Known Issue Rollbacks, or remediation KBs.
- Independent test benches and vendor statements if new reproducible variants surface; treat single-threaded anecdotal claims cautiously until corroborated.
Quick checklist — immediately actionable items
- Back up critical data externally. Firmware and OS upgrades are not the time to rely on a single copy.
- Run your SSD vendor’s dashboard tool and install any recommended firmware updates before attempting 25H2.
- If you manage Windows Update centrally, hold 25H2 for a pilot group and confirm firmware inventory across the fleet.
- Avoid forcing the enablement package if Windows Update flags a compatibility hold — do the remediation first.
Final assessment
The 25H2 compatibility hold for certain WD and SanDisk NVMe drives is a prudent, narrowly scoped safeguard rooted in a previously observed HMB/firmware interaction that produced serious outcomes for a subset of systems during the 24H2 cycle. Vendor firmware updates and Microsoft’s staged rollout protections together reduce the practical risk to users who follow the recommended steps: back up, update firmware, then accept the feature update through normal Windows Update channels.At the same time, the episode underscores larger systemic tensions: modern operating systems continuously evolve their low-level behaviors, and commodity storage firmware must be validated against those changes across many SKUs. The responsible path for users and IT teams is straightforward — prioritize firmware hygiene, respect upgrade holds, and adopt cautious pilot deployments — while recognizing that sensational narratives about widespread, irreversible bricking rarely survive rigorous vendor and lab testing.
For Windows users with WD/SanDisk NVMe drives, the recommendation is clear and simple: update SSD firmware through the official vendor dashboard, back up important files, and let Microsoft deliver 25H2 only after the compatibility hold clears for your device. That combination minimizes the chance of encountering a preventable failure and preserves a smooth upgrade experience.
Source: Пепелац Ньюс https://pepelac.news/en/posts/id4422-windows-11-25h2-blocks-upgrade-on-wd-sandisk-nvme-ssds/
