A series of Windows 11 users reflect that the latest update KB5063878 is causing serious errors with hard drives, causing data partitions to disappear and risking permanent data loss.

Windows 11 updates can cause hard drive errors that cause user data to disappear (Illustration: ITSFoss).
Last week, Microsoft released the KB5063878 update for Windows 11 to patch security vulnerabilities, specifically in response to the widespread Lamma malware.
However, right after this update was deployed, many users reported a serious error related to the hard drive.
According to records from forums and social networks, after installing update KB5063877 and performing operations to copy or move large amounts of data, the hard drive partition containing the data suddenly disappeared from the Windows system for unknown reasons.
This partition only reappears after restarting the computer, but disappears again if the user continues to copy large data.
More worryingly, some cases have recorded more serious errors where the hard drive partition disappears completely, even after restarting the computer, resulting in permanent data loss.
A preliminary survey shows that this error often occurs when users copy data continuously, especially when the total data size exceeds 50GB and the drive is more than 60% full of storage capacity.
This situation is especially common for gamers, who often have to update large game upgrades.
Initially, many thought that the bug only affected solid-state drives (SSDs), but it turned out that traditional hard disk drive (HDD) users were also experiencing the same issue. Many users have confirmed that uninstalling the KB5063878 update fixed the issue.
This error has been recorded on hard drives from many different manufacturers, including Western Digital, Phison, SanDisk… Hard drive manufacturer Phison (Taiwan, China) has confirmed the existence of the error and is investigating.
"Phison was recently notified of a Windows 11 update that may impact some storage devices. We have launched an investigation and are working with our partners to support and ensure remediation," a Phison representative said in a statement.
Microsoft has not yet commented on the issue. It seems that the bug is not widespread yet, and Microsoft may be in the process of reviewing the situation before officially acknowledging the bug and releasing a fix.
Source: https://dantri.com.vn/cong-nghe/ban-cap-nhat-moi-cua-windows-11-co-the-gay-loi-o-cung-lam-mat-du-lieu-20250820093920592.htm
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