Android: Microsoft apps lose MFA authentication

asked 2021-05-02T04:35:42.707+00:00
Falk 96 Reputation points

On my Android mobile phone (OnePlus 9 Pro, Android 11 latest release), I use several Microsoft Apps: Outlook (4.2114.2), Teams (1416/1.0.0.2021040701), To do, Office, OneDrive, OneNote, Authenticator (6.2104.2785). All of them are connected to my personal Microsoft account (Microsoft 365 w/ MFA + Hosted Exchange Plan 1 w/o MFA) and my employer's account (Hosted Exchange, Hosted Azure + MFA). At 3/1, my employer started to rollout MFA, so we had to add Microsoft Authenticator at https://aka.ms/mfasetup. We didn't have to register our devices with our employer, just add them as MFA devices. This all worked well for about seven weeks and still does for my Windows computer, btw.

Starting 4/21, all the Microsoft apps on Android seem to lose MFA authentication for my employer's account mulitple times per day. When this happens, I have scenarios like these: Outlook just won't sync with Exchange anymore (w/o any notice or request to re-authenticate). I still get Exchange push notifications, though, but can't open the emails I was notified about. Teams seems to be to stuck in an MFA loop: It suddenly pops up an empty window and immediately closes it again, about 250ms later it does this again and again in an endless loop, but won't log in. To do just won't sync w/o additional notice and so on.

After lots of trying I found out that force stopping Microsoft Authenticator "cures" the problem temporarily. Restarting my phone has the same effect. I must close Outlook, too, but after re-opening it, it starts to sync again immediately. For Teams I don't have to, it pops up the empty window, closes it and then seems to be logged in.

This is what I (unsuccessfully) tried:

  • completely wiping all cache and data of each Microsoft app and then removing them. Deleting all Microsoft accounts from my Android phone.
  • Using an older version of Microsoft Authenticator (I tried 6.2102.1274, 6.2104.2348)
  • In Authenticator: Registering my device with my employer (doesn't do any difference if I register it, it worked well w/o registration before 4/21. Currently, I have no registered device).
  • In Authenticator: After registration, enabling web access (doesn't do any difference)
  • Disabling battery optimization of Authenticator, so that it runs as service all the time (didn't have to do that before 4/21, btw - currently, battery optimization is disabled).
  • Disabling battery optimization of Outlook (it's enable again)
  • Removing all applications apart from Outlook and Authenticator, so that only these two log in (no difference at all)
  • Installed Microsoft in tune app (was a hint in a support thread): No difference (it removed it again, because we don't need it)
  • My company's admin resetted my MFA completely. W/o MFA, it worked like a charm, w/ MFA, the problems started to appear again
  • Connected Office Diagnostic tool on Windows computer to Android Office app: When Outlook won't sync anymore, it shows an error like "NoAuthentication" there

I am at my wit's end. Any help would be greatly appreciated, because this renders my mobile apps (that I all love and use constantly) unusable.

Thanks in advance!

Microsoft Authenticator
Microsoft Authenticator
A Microsoft app for iOS and Android devices that enables authentication with two-factor verification, phone sign-in, and code generation.
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Accepted answer
  1. answered 2021-05-08T05:32:49.943+00:00
    Falk 96 Reputation points

    It looks like 6.2105.3004 solved it for me. At least I didn't have the problem for about two days now which is promising.

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1 additional answer

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  1. answered 2021-05-02T19:54:17.603+00:00
    Vasil Michev 61,366 Reputation points Microsoft MVP

    There's a known issue with Authenticator, should be resolved in a coming version. In my case, switching to a different network helps, but your mileage will vary. But yeah, nothing to do apart from waiting for update, and praying MS will actually start testing things before inflicting them on their customers...