Today I was working with a client on an issue they were having with their Office 365 Pro Plus installation on their Windows Server 2019 Terminal Server. Somehow, a user, who did not have the appropriate Office365 license assigned to them, had logged into their account on the terminal server and now the product was not activating for all users.

All users were were seeing the following error message when signing into their Microsoft account:

I knew that the wrong account was logged in on this computer because when I would launch Word, even though it was telling me to log into my Microsoft Account to activate the product, I would see the previous user’s account name in the upper right hand corner of the the application.

So I tried all the normal things:

• • Browsing to portal.office.com and logging out
  • Restarting the computer
  • Deleting all saved credentials from the Windows Credential Manager
  • Logging into portal.office.com with the correct account and downloading a fresh installer
  • Even a complete uninstall and reinstall of the Office Application. 

Nothing would allow me to successfully log in with the correct Office365 user account. So it was clear the it was caching the credentials somewhere. 

I finally found this helpful Microsoft article that detailed where in he registry the stored credentials were saved:

HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Identity\Identities

Under that key you will see all the saved Microsoft Office365 Profiles. I went ahead and deleted all the saved profiled and now I was able to successfully log in and activate Office365 on this Windows Server 2019 Terminal server.