Also, at the time, that user did not have MFA turned on. In the instances that this occurs the effected user is not new to MFA but has been running it for at least months. The problem appears to randomly affect users (I’ve had it affect myself once too), and the only solution appears to one of (or a combination of) the options in the OP. Out of 140 staff the problem seems to occur once every 2-3 weeks on average.

Additional resources

The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action. Create your account and connect with a world of communities. I cannot find the phone number again to contact MS Office support (eventually they were helpful, but only after insisting they help!), I'm in the Netherlands so if someone has a phone number, I'd love to get it again.

Microsoft Office 365 Endless Authentication Loop Issue

• I even tried disabling my anti -virus while authenticating, that didn't work.
• We too have been seeing this more and more, all W10 on O365, although we use Okta as our MFA.
• Microsoft Outlook 2016 and some recent builds of Outlook 2013 are not affected by this issue.
• If this box is greyed out or disabled then you need to reset the Windows Credential Manager first.
• We had the issue where Outlook 2016 kept prompting for a password for an Office 365 user whose laptop was connected to their Office 365 account using Windows 10 Pro.
• The repeated issue logging in started after I enabled the modern authentication in the Office 365 administration panel.

You may have to rebuild/restore your outlook folder/files which is a pain. I’d do that one step at a Outlook Login Issues Troubleshooting 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 modern authentication troubleshooting 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

You can reply to reactivate the question if you decide you want to continue. Let's Outlook profile repair and recovery steps start by answering a few simple questions to understand the problem. We have been experiencing the exact same issue for months now. I experience the issue myself as well, every once in a while. On the off chance that none of these things solve this issue for you, please contact our support team at