But by mistake, I turned on MFA for the admin account, and then when I logged in again, it prompted me to use Microsoft Authenticator. The bad thing is this account was not registered with Microsoft Authenticator, so I couldn't see any codes Office 365 sync problems and login fixes in the authenticator. And there were no other login options, and I was stuck in a login loop. 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.

Outlook credential prompt loop

I disabled the Zoom and Adobe PDF plugins and it stopped prompting me immediately. My client’s Outlook will only continuously ask for the password clear Outlook credentials manager after MFA is enforced and Office.com has been logged in. It would be nice if it distinguished between your password and the app password. You may have to rebuild/restore your outlook folder/files which is a pain. I’d do that one step at a time, forgoing the restore of the cached files. Not sure if it has to do with being an onmicrosoft.com account that has no domain assigned to it.

Loop of 'Sign in to your account'.

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. The user could use the Windows mail and calendar apps but Outlook wouldn’t connect and kept prompting for a password. Checking the Account in Word showed the correct authentication and subscription.

Resetting the Windows Credential Manager:

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. We’ve got a support case opened with Microsoft on this one but it’s been FixTechGuide email error solutions open for about 3 months. Unfortunately when the problem occurs they’ve asked us to ring straight away but of course you can never get them instantly (we’ve just been given someone’s direct number now). To make a long story short we’ve since been asked to collect Outlook logs and install Fiddler to capture additional logging. Initially, this account didn't have MFA turned on, and I was able to log in.

• If this box is greyed out or disabled then you need to reset the Windows Credential Manager first.
• FYI outlook 2013 requires a registry setting to work with MA.
• I created a new Outlook profile, and then the old one started working.
• When I log in to my account at first from a new device or after a while, it stays signed in and I can work peacefully for about an hour, then it automatically signs me out.
• Out of 140 staff the problem seems to occur once every 2-3 weeks on average.
• But by mistake, I turned on MFA for the admin account, and then when I logged in again, it prompted me to use Microsoft Authenticator.
• I experience the issue myself as well, every once in a while.

Changing Outlook Security Settings:

If this box is greyed out or disabled then you need to reset the Windows Credential Manager first. @Microsoft, given the level of attention the community has given this issue, I hope you come up with an update soon. We have been experiencing the exact same issue for months now.