Users of perpetual Office 2016 and 2019 licenses are reporting that their installations have suddenly lost activation status, triggering repeated prompts to enter a product key and warnings that reduced functionality is coming. The issue appears to have started this week and is mostly affecting Home and Business editions. Many affected users point to KB5002907, an optional update for Windows PCs running Microsoft 365 Apps that are more than 90 days out of date. Microsoft says the update is meant to help those apps resume updating, and stresses it is not automatic.
Re-entering the original product key can restore activation, but that is impractical for organizations managing hundreds or thousands of devices. One reader told The Register the issue "took out our Office 2016 installations" and required multiple reactivations, restarts, and account sign-in/out cycles to stabilize. Microsoft has not confirmed whether the update is responsible.
Office 2016 and 2019 reached end of support on October 14, 2025, so Microsoft is under no obligation to fix them. The company has previously shipped patches that broke older software, and in the case of Office 2019 on Mac, deliberately dropped apps into reduced functionality mode by letting a certificate expire. Microsoft had assured users they could continue using Office 2016 and 2019 after support ended, but did not mention the possibility of activation failures.