Microsoft Warns September 2026 Windows Updates Can Break File History Backups

Summary

Microsoft says September 2026 Windows security updates may stop File History backups from creating or updating on some Windows 10 and 11 systems, with crashes, false reconnect prompts, and missing previous versions reported.

Key points

The September 2026 Windows security updates may prevent File History from creating or updating backups on affected systems.
Symptoms include FileHistory.exe and KERNELBASE.dll crash events, false “Reconnect your drive” prompts, and a Last Backup timestamp that does not update.
Previously backed-up files may show “No previous version available,” limiting users’ ability to restore older copies.
Affected releases include Windows 10 21H2 or later, Enterprise LTSC 2016/2019, and Windows 11 23H2 or later; the article lists the corresponding originating KBs.
Microsoft’s alert, as reported by BleepingComputer, describes the issue; the article does not provide a fix for the File History problem.
Microsoft said separate out-of-band updates addressed some other problems from the September updates, while some audio issues remained unresolved.

Article Details

Event Type: Post-update software malfunction affecting Windows File History backups
Impact: Microsoft warned that some systems may be unable to create or update File History backups after installing the September 2026 Windows security updates. Affected users may see FileHistory.exe and KERNELBASE.dll crash events, false drive-reconnection prompts, stale backup timestamps, and unavailable previous file versions. The article identifies affected Windows 10 and Windows 11 releases, including Enterprise LTSC versions.

People

Susan BradleyMicrosoft MVP who first spotted the Microsoft service alert, according to the article.

Vendors

MicrosoftMicrosoft warned that the built-in File History backup feature in Windows may stop working on some systems after the September 2026 security updates.

Products

File HistoryMicrosoft warned that the built-in File History backup feature in Windows may stop working on some systems after the September 2026 security updates.Microsoft WindowsMicrosoft warned that the built-in File History backup feature in Windows may stop working on some systems after the September 2026 security updates.