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Right now we have it set to prompt when a user is not on any of our corporate networks or they are using a mobile device. To locate and view the registry setting for Anonymous Authentication in the Outlook profile, follow these steps. This issue can occur if the Logon network security setting on the Security tab of the Microsoft Exchange dialog box is set to a value other than Anonymous Authentication. Today was the first time in about 2 months that I had the issue. It happened right before lunch, locked my machine, went out for lunch, came back, and logged in, this time successfully.
Additional resources
This is now the 2nd machine that presents the same issue. I have a valid MS 365 subscription that includes 5 device licenses. On the main machine where I have been using the suite, now my account is deactivated and if I try to authenticate, it looks like it works but then get the "Fix", "Authenticate", "Activate" or "Resolve" buttons, all of which do nothing. I checked my MS account info page, subscription is fine. I had this exact issue on another machine, that after 2.5 hours on the phone with MS support (via Zoom), the solution was to uninstall MS Office 365 and reinstall it.
Microsoft Office 365 Endless Authentication Loop Issue
Today was the first time in about 2 months that I had the issue.I experience the issue myself as well, every once in a while.In each case the fix has either been one of the above items or a combination of them.I then approve the login with my authenticator app.Outlook must be online or connected to complete this action.So figuring that was the same issue here, I did the same thing.Those versions have been updated to prevent the problem that is described in the "Symptoms" section.If you are saying that they are getting multiple MFA prompts then this is an out of sync issue with the wrong code being used.
You may have to rebuild/restore your outlook folder/files which is a pain. I’d do that one step at a credential loop in Microsoft 365 time, forgoing the restore of the cached files. If this box is greyed out or disabled then you need to reset the Windows Credential Manager first. Or, any suggestion on how to fix this issue, even better.
Outlook stuck in an MFA loop
The Troubleshoot Office 365 Sync and Login Issues user had Office 2015 and Office 2016 credentials and Teams credentials that we deleted. We checked with Word that the account was connected–it was and the we opened Outlook and it immediately connected. We too have been seeing this more and more, all W10 on O365, although we use Okta as our MFA. Have looked all over and people have all sorts of possible solutions, but nothing we found to resolve the issue and get a new issue daily and just keep going through until it eventually works. I’ve seen this happen when the time and or date is wrong on the machine. It’s not caused by an out of sync MFA prompt as I have personally looked at a number of cases with the user as stepped through it.
Outlook 365 Password Prompt Issue on Windows Desktop
So not doing anything at all even seems to work. Which to me sounds flush DNS and re-sync Outlook like the issue is service side, not client side. Problem doesn’t just happen on PC’s connected to the internal network, but can happen when a laptop is remote and connected via external wifi or mobile hotspot.