Microsoft patches File History breakage from September 2026 updates; Always On VPN bug still awaiting fix

Microsoft's September 2026 security updates broke File History backups on Windows 10 and 11 and Always On VPN connections on Windows 11; the File History bug is now fixed via optional updates KB5124006 and KB5124010, while the VPN issue has only a temporary…

Microsoft's September 2026 Windows security updates introduced multiple regressions. They broke the built-in File History backup feature on Windows 10 21H2 and later, Windows 10 Enterprise LTSC 2016 and 2019, and Windows 11 23H2 and later, causing FileHistory.exe crashes against KERNELBASE.dll, false 'Reconnect your drive' alerts, outdated 'Last Backup' timestamps, and an inability to create or update backups; Cyber Security News reports Microsoft documented the issue with KB5124008 and KB5124012. On September 24, 2026, BleepingComputer reported Microsoft resolved the File History issue with optional cumulative updates KB5124006 (Windows 11 26H1) and KB5124010 (Windows 11 24H2 and 25H2), with the fix reaching all other systems on the October 13 Patch Tuesday; Microsoft advised users to manually verify backup contents in the meantime. The same update cycle also broke Always On VPN connections on Windows 11 24H2, 25H2, and 26H1 when automatic protocol selection (IKEv2/SSTP) is enabled, causing connections to fail or display port errors; Microsoft's temporary workaround is switching to a single VPN protocol while a permanent fix is developed. The September updates had already required out-of-band fixes for Remote Desktop, Hyper-V, and USB audio issues.

• September 2026 Windows security updates broke File History on Windows 10 21H2 and later, Windows 10 Enterprise LTSC 2016 and 2019, and Windows 11 23H2 and later.
• File History symptoms include FileHistory.exe crashes against KERNELBASE.dll, false 'Reconnect your drive' alerts, outdated 'Last Backup' timestamps, and failure to create or update backups.
• Cyber Security News reports Microsoft documented the File History issue under KB5124008 and KB5124012.
• Microsoft shipped optional fixes: KB5124006 for Windows 11 26H1 and KB5124010 for Windows 11 24H2 and 25H2; devices that skip them receive the fix on October 13, 2026 Patch Tuesday.
• Microsoft advised affected users to manually verify backup contents and consider alternative backup solutions.
• September 2026 updates also broke Always On VPN on Windows 11 24H2, 25H2, and 26H1 when automatic protocol selection (IKEv2/SSTP) is enabled, causing failed connections or port errors.
• Temporary Always On VPN workaround: switch to a single protocol (IKEv2 or SSTP); Microsoft is developing a permanent fix.
• The same update cycle previously required out-of-band fixes for Remote Desktop, Hyper-V, and USB audio issues.