
Windows File History Backup Fails on September 2026 Patch Hit
Microsoft warns that September 2026 security updates may cause Windows File History backups to fail or not update on affected systems (Windows 10 21H2+ and Windows 11 23H2+). Symptoms include crash events in Event Viewer (FileHistory.exe and KERNELBASE.dll), false “Reconnect your drive” prompts, and backup timestamps or previous versions not updating. The issue spans multiple KBs across affected Windows versions. Microsoft has released out-of-band updates to fix other problems introduced by the September updates, but a fix for File History-related backup failures is still being worked on.












