Office 2016 and 2019 holdouts blame an update for license deactivation bug

Users report that a recent optional update for out-of-date Microsoft 365 applications may be connected to suddenly deactivated Office 2016 and 2019 installations, The Register reports. The activation bug cropped up this week and appears to affect mostly Home and Business perpetual license installations.

A previously activated copy of Office 2016 or 2019 abruptly loses its activation information, so the application starts asking the user to re-enter the product key. Pop-ups warn that functionality loss is imminent, and yellow banners tell users how many days are left before the apps stop working. One fix is to re-enter the original product key to restore the activation state.

What users are seeing

A Register reader said the issue "took out our Office 2016 installations." They added: "First indication is a message in the app you are using telling you that normal functionality has been removed. Also yellow banners saying you have five days left before you can no longer use the apps."

"It takes multiple product reactivations, restarts and sign in/sign out of your Office account to get it stable," the reader said. That is manageable on a single machine, but far harder across dozens, hundreds or more devices.

Eyes on KB5002907

Many users online believe the problem is connected to KB5002907, an optional update for Windows PCs with Microsoft 365 Apps that are more than 90 days out of date. According to Microsoft, "Installing the update can help the apps resume updating and move to a current build for the device's assigned update channel." The company also said the update is not automatic.

Affected users noted that the reactivation demands began around the same time the update appeared. Microsoft has not confirmed a link between the update and the deactivations.

A troubled history

Support for Office 2016 and 2019 ended on October 14, 2025, so Microsoft is under no obligation to keep shipping updates. That has not stopped the occasional patch from breaking things: paste problems surfaced after an Excel update and were fixed on September 18, 2026. In June, the Apple version of Office 2019 was deliberately dropped into reduced functionality mode when a certificate expired.

When Office 2016 and 2019 for Windows reached the end of support, Microsoft assured users they could continue using the products regardless. It did not mention that they might one day have to enter their product activation code again.