A few customers had an issue where their Teams Addon in Outlook for MacOS would stop functioning after MFA activation on exchange. When trying to make a calendar invite with MS Teams integration they would get an message saying “Authentication required”. To be more exact “Outlook needs to confirm your account permissions before adding a Teams Meeting. Please login..”. After clicking “OK” on that popup, it would still fail.

Went through a ton of different answers from Google like:

  • Log out of both Outlook and Teams & then log into Teams before opening Outlook
  • Delete Outlook user and then re-add it to Outlook (Helped in one instance)
  • Delete some key chain entries

Those didn’t help one bit in that case. What actually fixed the issue was removing the Office 365 license and re-activating Office.

To remove the MS Office license just close all MS Office applications and download the removal tool from Microsoft and follow their guide here: How to remove Office license files on a Mac – Office Support (microsoft.com)

After removing the license re-open Outlook , it should prompt You to insert Your O365 licensing related credentials again. After doing that retry making a calendar invite and use the Teams Addon. A familiar “Authentication required” window should pop up. Click OK on it again, but this time the authentication process should actually start and work. After that it should continue working with out a hitch.

There was actually one instance where the license removal trick didn’t help. There I retried the account removal and that fixed it for that user.