On August 12, 2025, Microsoft rolled out the Windows 11 version 24H2 security update, designated KB5063878. This update aimed to resolve a significant issue where users experienced delays when signing into new Windows 11 devices, a problem attributed to “certain preinstalled packages.” However, the update was not without its own complications. Some users encountered an installation error marked by the code Ox80240069, which Microsoft identified as stemming from attempts to deploy the update via Windows Server Update Services (WSUS). Fortunately, this issue has since been addressed.
Yet, a more alarming concern has emerged, as highlighted by X user @Necoru_cat (known as Nekorusukii). They reported that the update not only caused solid-state drives (SSDs) and hard-disk drives (HDDs) to vanish from the operating system but also resulted in data loss so severe that recovery was impossible for some users.
What you need to know about storage issues with Windows 11 update KB5063878
Nekorusukii’s testing revealed that drives could become inaccessible in Windows 11, with SMART data rendered unreadable. While it might be possible to access the buffered tree, files themselves remain unreadable. This troubling issue appears to arise when large amounts of data are written to specific drives, particularly when the file size exceeds 50GB and the drive is over 60% full. Both SSDs and HDDs seem susceptible to this glitch.
In instances where users encounter this problem, a system reboot may restore the drive’s functionality. However, the issue can reoccur if the drive is subjected to similar stress again.
During their investigation, Nekorusukii tested 21 SSDs from various manufacturers, including Samsung, WD, Seagate, Corsair, SK hynix, Crucial, Solidigm, ADATA, HP, XPG, and Hanye. Their findings suggest that the Phison NAND controller is likely at the heart of the problem.
(Image credit: @Necoru_cat (X))
Nekorusukii meticulously restarted their PC after each test to clear the drive’s cache. They created a 62GB file, compressed it into a 7-Zip archive, and wrote it to the SSD. The subsequent decompression of the archive on the tested SSD yielded a chart where NG Lv.1 indicated an SSD failure that was recoverable after a reboot, while NG Lv.2 signified an unrecoverable error even post-reboot. Remarkably, only the WD Blue SA510 2TB SATA SSD was rendered unrecoverable, with several other drives disappearing from the OS but reappearing after a reboot.
These tests were conducted on a single PC, leaving the overall prevalence of the issue uncertain. Moreover, it remains unverified whether the Windows 11 updates KB5063878 or KB5062660 are indeed the root cause.
Phison has recently been made aware of the industry-wide effects of the ‘KB5063878’ and ‘KB5062660’ updates on Windows 11 that potentially impacted several storage devices, including some supported by Phison. We understand the disruption this may have caused and promptly engaged industry stakeholders. We are steadfast in our commitment to product integrity and the success of our partners and end users. At this time, the controllers that may have been affected are under review and we are working with partners. We will continue to provide updates and advisories to partners who may have been impacted to provide support and ensure any applicable remediation.
Phison
While reports of this storage issue do not appear to be widespread, Tom’s Hardware has uncovered additional users experiencing similar problems, as noted by NichePCGamer. This expanded list of potentially affected SSDs includes:
- Corsair Force MP600
- SSDs utilizing the Phison PS5012-E12 controller
- KIOXIA EXCERIA PLUS G4 / KIOXIA M.2 SSDs
- Fikwot FN955
- SSDs using the InnoGrit controller
- Maxio SSDs
- SanDisk Extreme Pro 3D
For those navigating these challenges, it is prudent to refrain from large, continuous file transfers on systems running Windows 11 with update KB5063878, particularly if utilizing any of the aforementioned drives.
Yet another reminder to back up your data
(Image credit: Windows Central)
In light of these developments, the importance of data backup cannot be overstated. Recent incidents involving high-profile data loss have underscored the risks of relying solely on cloud storage. While some users managed to recover their data after disruptions, others faced irreversible losses.
To mitigate such risks, adhering to the 3-2-1 backup rule remains a sound strategy. This principle suggests maintaining three copies of your data: two stored on different media types and one kept off-site to guard against localized disasters. In today’s cloud-centric world, this could translate to having one copy on your PC’s internal storage, another on an external drive, and a third in the cloud.
