Office 2016 and 2019 disabled due to optional update

Since September 24 and 25, 2026, reports have been accumulating that the optional update KB5002907 is causing purchased full versions of Office 2016 and Office 2019 to lose their licensing.

Affected are only perpetual licenses such as Home & Business, Home & Student, or Professional Plus, not Microsoft 365 subscriptions. On the devices, either the message "Unlicensed Product" appears, Office switches to read-only mode, or the applications disappear completely from the system after a restart.

KB5002907 is titled 'Update support for older Microsoft 365 Apps installations' and appears in the German update history as 'Click-to-Run-Updateunterstützung.' It is designed to bring outdated Click-to-Run installations of Microsoft 365 Apps—those that haven't received updates for more than 90 days—back on track.

However, in practice, it also appears to take effect where no Microsoft 365 is in use—only a one-time purchased Office version.

The technical bridge is likely the common foundation: Microsoft 365 Apps, Office 2019, and Office 2016 share the same product version 16.0, the same Click-to-Run technology, and the same Group Policy templates. An update intended solely for Microsoft 365 Apps can, via this shared installation layer, also affect a perpetual installation.

Microsoft has neither confirmed this nor officially declared it a bug. Since Office 2016 and 2019 have been out of support since October 2025, there is no obligation to provide a fix.

The update is not automatically deployed to every system. Those who install it manually or via an optional update path are more likely to end up on the error path. On machines running Office 2016 or 2019, you should therefore deliberately postpone KB5002907 until Microsoft provides a fix.

If the damage is already done, reactivation with the original product key or signing in again with the linked Microsoft account usually helps. If Office has been completely removed, you must reinstall the exact same edition and reactivate it via the original licensing path, such as through the account or the Workplace Discount Program.

This is exactly where it gets expensive in day-to-day operations: Without a readily available key, searching for license documentation across multiple devices takes more time than the update itself.

KB5002907 is an optional update with an unintended side effect on deprecated but still productive Office versions. Check your inventory for Office 2016 and 2019, have the product keys ready, and block the update on these devices until a fix is available.

Those who already have M365 Apps licenses are using the incident as an opportunity to switch to the modern, continuously updated version.