Users reported that the optional KB5002907 update for Microsoft 365 caused the deactivation of perpetual licenses for Office 2016 and 2019. The issue, identified on September 24, 2026, primarily affects Home & Business editions on Windows 11 systems that had not been updated for over 90 days.
Although the update is classified as optional, some users reported it installed automatically. Christian Van Hautte, owner of Solid Systems, noted that several of his clients experienced sudden license loss simultaneously. In some instances, the update process led to the complete removal of Office applications from the hard drive.
The removal issue appears to occur on systems mixing 32-bit and 64-bit Office components, such as having a 64-bit Microsoft Access Runtime alongside 32-bit Office versions. The installer attempts to reinstall the software but fails due to architecture incompatibility, requiring users to perform a manual reinstallation.
Microsoft has acknowledged the problem and suspended the distribution of the KB5002907 patch. While some users were able to resolve the deactivation by re-entering product keys or logging into their Microsoft accounts, others faced more severe installation failures.
