Microsoft Fixes File History Backup Failures After September Updates
Microsoft has fixed an issue that stopped File History backups from working on some Windows PCs after the September 2026 security updates were installed.
The fix is included in the optional KB5124010 and KB5124006 cumulative updates for Windows 11, and Windows 11 users who skip these optional updates will receive it with the October 13 Patch Tuesday release.
Microsoft first warned about the problem on its Windows release health dashboard and listed Windows 10 21H2 and later, Windows 10 Enterprise LTSC 2016 and 2019, and Windows 11 23H2 and later as affected versions.
Users who see 'Reconnect your drive' alerts even when a compatible backup drive is connected may have been impacted by the bug. Files that were backed up earlier can show 'No previous version available,' and the 'Last Backup' timestamp stops updating.