Microsoft confirmed that its September security updates for Windows 10 and Windows 11 contain a bug that breaks the File History backup feature. This issue directly impacts users who rely on automatic file versioning and backup routines, potentially leaving their data unprotected against loss or corruption. We recommend checking your backup status immediately if you have installed the recent patches.
Uninstall KB5124008 and KB5122878 to restore backups
The bug affects specific versions of the operating system, including Windows 10 versions 21H2 and 22H2, as well as Windows 11 versions 23H2, 24H2, 25H2, and 26H1. Microsoft identified the problem in security updates KB5124008 and KB5122878, which were released as part of the standard monthly security cycle. The updates introduce a bug that causes File History backup failures on these platforms.
Users experiencing the issue may encounter error messages such as 'Reconnect your drive' or 'No previous version available' even when external drives are properly connected. The system may also log application crash events involving FileHistory.exe and KERNELBASE.dll. These errors indicate that the backup service cannot access or write to the designated storage location.
Microsoft is currently working on a fix for this File History bug and plans to distribute the solution through a future Windows update. In the meantime, the official workaround is to uninstall the problematic September updates via Windows Settings. Users should remove KB5124008 and KB5122878 to restore normal File History functionality until the patch is available.
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