Office 2019 Lost Authentication And Just Gets An Error Trying to Re-Authenticate

Hi, Duncan Harrison

This is probably not a normal sign-in problem. A licensing change that took effect on July 13, 2026 can place Office 2019 for Mac into reduced-functionality mode, and support for Office 2019 ended in October 2023.

Here are some suggestions you can try:

Open Word and select Word > About Word. If it shows Office 2019, version 16.78 was the final build that supports an Office 2019 license, so reinstalling or repeatedly clearing credentials may not fix this particular issue.

Sign in to Services & subscriptions using the Microsoft account originally used to redeem Office. Confirm that Office 2019 is still listed there.

If the license is listed, it is worth running the official Office License Removal Tool once, restarting the Mac, and signing in again with that same account.

If activation still fails, the practical options are using Office on the web temporarily, or moving to Office 2024 or Microsoft 365. Contact Microsoft support with the purchase receipt if the license has disappeared from the account.

Please be advised that this is a user-to-user support forum. Moderators and contributors, including external Microsoft employees, are not allowed to directly interfere with Microsoft product features or access back-end systems. Our role is limited solely to providing technical guidance on reported incidents, requests, or ideas.   

Thank you for your patience in reading, I hope this information has been helpful to you. 

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