I experience the issue myself as well, every once in a while. Tried CC cleaner to clean up registry and everything -- also keep in mind this repair corrupted OST in Outlook is a fairly recent reinstall of windows. I am unable to stay signed in to my work account on Teams, Outlook, Office365 for more than 5 minutes.

Outlook credential prompt loop

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. In this case are you saying that there is a password prompt for the users credentials? Clear the Windows Credential manager or recreate the users Outlook profile. In fact if you just turned on MFA and you were not using MFA before you usually end up having to rebuild Outlook OST vs PST repair the profile and clearing the credential manager.

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:

I have contacted my organization and everything looks alright from their end.. I went as far as getting a new device but it did not cut it. When I try to sign again it will be stuck in sign in loop with the message " Taking you to your organization sign in page" after I have logged in on my company site... 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. Or, any suggestion on how to fix this issue, even Fix Outlook and Office365 Sync Issues better. I do NOT have this issue with the other laptop, an iPad, a MacBook Pro and tablet.

• 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.
• 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'm also getting Error 29, which the MS support rep couldn't explain to me.
• I experience the issue myself as well, every once in a while.

Changing Outlook Security Settings:

Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. 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.