Microsoft Warns Windows File History Feature May Fail After September Security Patch

REDMOND, Wash. — Microsoft issued a warning Tuesday that the built-in File History backup feature in Windows may cease functioning on certain systems following the installation of the company's September 2026 security updates. The software giant advised users to verify their backup configurations immediately to prevent potential data loss.

The issue stems from changes introduced in the latest monthly security patch, which was distributed globally on Tuesday. Microsoft stated that while the update addresses critical vulnerabilities across its operating system ecosystem, it inadvertently disrupts the File History service on specific hardware and software configurations. The feature, designed to automatically save copies of user files to external drives or network locations, is a primary recovery tool for many personal and enterprise users.

In a technical advisory released at 12:04 p.m. UTC, Microsoft confirmed that the failure occurs when the updated system attempts to initialize the backup service. Users may find that scheduled backups do not run, or that the feature disappears from the settings menu entirely after a reboot. The company emphasized that this is an isolated incident affecting only the File History utility and does not impact other backup solutions or third-party software.

Microsoft has not yet released a specific list of affected Windows versions or hardware models, noting that the problem appears sporadic across different deployments. The tech giant urged users who rely on File History to manually test their backup routines before deleting any local copies of critical data. "We are actively investigating the root cause and working on a resolution," the advisory stated.

For users experiencing the disruption, Microsoft recommended temporarily disabling the automatic update feature or rolling back the September patch until a fix is available. However, the company cautioned that reverting security updates leaves systems exposed to known vulnerabilities addressed in the September release. IT administrators were advised to monitor their networks for backup failures and consider alternative data protection strategies in the interim.

The warning comes as Microsoft continues its routine cycle of monthly security patches, which are essential for protecting against emerging cyber threats. The disruption highlights the complex balance between deploying rapid security fixes and maintaining the stability of core operating system features. As of Tuesday afternoon, no official timeline has been provided for a permanent resolution or a cumulative update to address the File History regression.

Questions remain regarding the scope of the impact and whether other backup mechanisms within Windows are susceptible to similar conflicts. Microsoft indicated it will provide further updates as more information becomes available from its engineering teams.