Activation failed

This matches the Microsoft 365 for Mac licensing-certificate change that took effect on July 13, 2026. Older Office builds enter reduced-functionality mode, so they can open files but cannot edit or save. Excel 16.7.1 is well below the required current build.

In Excel, choose Help > Check for Updates, select Update All, and update to version 16.110 or later. If Office came from the Mac App Store, update it there instead. Quit and reopen all Office apps, then sign in with the account that owns the active subscription.

If AutoUpdate is missing or will not update, reinstall Microsoft AutoUpdate (or reinstall Microsoft 365 from your account) and try again. Only if activation still fails after updating, run Microsoft's Office License Removal Tool and reactivate.