Microsoft September Updates Break Windows File History Backup

Microsoft has issued a warning that the native File History backup functionality within Windows may cease to operate correctly on certain systems following the installation of the September 2026 security updates. This issue specifically impacts the ability of File History to perform backups, potentially leading to data loss if users rely solely on this feature for system recovery or file versioning. The company has not yet provided a specific timeline for a fix, but has acknowledged the problem and is investigating its root cause.

File History is a built-in Windows feature designed to automatically back up personal files stored in user libraries, such as Documents, Music, Pictures, and Videos, as well as the Desktop. It works by saving versions of files to an external drive or network location, allowing users to restore previous versions of files or recover deleted files. The September 2026 security updates, released by Microsoft to address various vulnerabilities and enhance system security, appear to have introduced an unintended side effect that interferes with the operational integrity of File History.

While the exact number of affected systems or the specific conditions under which the failure occurs have not been detailed by Microsoft, the company's advisory suggests a broad potential impact. Users who have installed the September 2026 updates and subsequently notice that File History is not performing backups, or is reporting errors, should be aware that this is a known issue. Microsoft recommends that affected users consider alternative backup solutions as a temporary measure until a permanent fix is deployed. This situation highlights the ongoing challenges in maintaining system stability and functionality while simultaneously implementing critical security patches, a common balancing act in software development.

Microsoft has not specified which particular security updates within the September 2026 release are responsible for the File History malfunction. The company typically releases cumulative updates on a monthly basis, often referred to as "Patch Tuesday," which include a mix of security fixes and non-security improvements. The File History feature has been a part of Windows since Windows 8, and its disruption, even if temporary, can cause significant concern for users who depend on it for data protection. The company's official support channels are expected to provide further updates as the investigation progresses and a resolution is developed. Users are advised to monitor Microsoft's support website for the latest information and guidance regarding this issue.