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 FixTechGuide support for Office 365 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

So figuring that was the same issue here, I did the same thing. I'm also getting Error 29, which the MS support rep couldn't explain to me. I even tried disabling my anti -virus while authenticating, that didn't work. On the off chance that none of these things solve this issue for you, please contact our Office 365 sync problems and login fixes support team at

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:

When we opened the old, existing profile it didn’t ask for ANY authentication, it just started working. Office 2016 is already Modern Authentication aware so APP passwords are not required. Native IOS and Android Mail apps will require the APP password or users can use Outlook for IOS/Android which is Modern Auth aware. FYI outlook 2013 requires a registry setting to work with MA. Where I work, we have a new sandbox tenant to make tests before send/receive error 0x800CCC0E fix official deployment. I tried registering the account to my Outlook Desktop app and for some reason I am in a credential prompt loop that always asks for it anytime I input my password.

• 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.
• 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.
• On the off chance that none of these things solve this issue for you, please contact our support team at
• Not sure if it has to do with being an onmicrosoft.com account that has no domain assigned to it.
• Hi, my office 365 account used to work with my desktop apps, I have confirmed with my admin system twice already that I have the appropriate license and everything is enabled but i keep getting stuck in this loop.
• Checking the Account in Word showed the correct authentication and subscription.
• Native IOS and Android Mail apps will require the APP password or users can use Outlook for IOS/Android which is Modern Auth aware.

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.