Microsoft has issued a cautionary note regarding the built-in File History backup feature in Windows, indicating that it may experience functionality issues on certain systems following the installation of the September 2026 security updates.
Understanding File History
File History, which was first introduced in Windows 8 and later succeeded by Windows Backup for OneDrive integration, is designed to automatically save copies of files. This feature enables users to recover files that may have been accidentally deleted or damaged, allowing access to earlier versions from hours, days, or even weeks prior.
By default, File History backs up all folders under a user’s account profile, including Documents, Music, Pictures, Videos, and Desktop, to an external hard drive or a network-attached storage (NAS) device.
In a service alert reported by BleepingComputer and initially identified by Microsoft MVP Susan Bradley, the company acknowledged that users experiencing issues may notice application crash events in the Event Viewer, specifically referencing FileHistory.exe and KERNELBASE.dll.
Microsoft stated, “After installing the September 2026 Windows security update (the Originating KBs listed above), some customers using File History might be unable to create or update backups.” The feature can be accessed via Control Panel > System and Security > File History, where users typically manage their backup settings.
On affected systems, users may also encounter misleading messages such as “Reconnect your drive,” even when compatible backup drives are properly connected and functioning. Additional symptoms include the “Last Backup” timestamp failing to update and previously backed-up files displaying “No previous version available.”
The impacted Windows versions include:
- Windows 10 21H2 or later
- Windows 10 Enterprise LTSC 2016/2019
- Windows 11 23H2 and later
The September 2026 cumulative updates have been associated with a range of issues affecting both home and enterprise users of Windows. Just a week ago, Microsoft released out-of-band updates aimed at addressing failures in Remote Desktop Services, Hyper-V issues, and USB audio problems stemming from this month’s security updates.
However, the company has confirmed that these emergency updates did not resolve all audio-related problems introduced by the September 2026 updates, and efforts are ongoing to address the remaining issues. Additionally, Microsoft has provided a temporary workaround for a separate bug that prevents some Windows 11 users from logging in with valid domain credentials after the installation of the September updates.
