Microsoft has acknowledged that its September 2026 Windows security updates may prevent File History from creating or updating backups on certain systems This article explores principle backup reliable. . This regression poses a risk for users relying on the built-in feature, as it could lead them to assume their files are protected when no recent backup has actually been completed.
It copies files to an external drive or network location, retaining earlier versions, allowing users to recover accidentally changed, corrupted, or deleted documents. Computers affected by a "Reconnect your drive" warning despite a connected backup disk and operational files could indicate issues with the File History interface's "Last Backup" timestamp. Review the Event Viewer for crashes involving two specific components.
Although some users claim KB5124008 restores File History, uninstalling a security update can reopen vulnerabilities addressed by the patch and should not be considered a low-risk fix. Until Microsoft releases a fix, affected users should maintain a separate, verified backup using another trusted product or a controlled manual copy process. Organizations should monitor endpoint backup success, alert on stale timestamps, and test restoration to ensure trustworthiness, rather than relying solely on job status.
This incident underscores a fundamental resilience principle: a backup is reliable only after independent validation of its contents and recovery path.
