I feel like this issue is getting progressively worse as the fix used to be Fix Outlook Not Opening After Windows Update clearing the credential manager or if it was bad uninstalling the entire Office Suite, clearing all traces and reinstalling and now we are seeing nothing helping it. 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. 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. 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.

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 Exchange connectivity diagnostic support team at

Loop of 'Sign in to your account'.

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. Yeap, you describe it exactly and unfortunately we still don’t have an answer. Closed the window without entering anything and Outlook returned to ‘Connected to Exchange’. I created a new Outlook profile, and then the old one started working. I wonder if the compuer cached a new logon token or something that the old Outlook profile could use. Also, during the new profile creation, I was only prompted for a password and not for MFA.

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 Repair Outlook Profile Online 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.

• 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.
• Where I work, we have a new sandbox tenant to make tests before official deployment.
• I do NOT have this issue with the other laptop, an iPad, a MacBook Pro and tablet.
• 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.
• 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.

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.