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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 the profile and clearing the 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.
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Please help can't afford a new computer if I throw this one against the wall. 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’. Office 2016 is already Modern Authentication aware so APP passwords are not required.
Microsoft Office 365 Endless Authentication Loop Issue
I even tried disabling my anti -virus while authenticating, that didn't work.Microsoft Outlook 2016 and some recent builds of Outlook 2013 are not affected by this issue.We have been experiencing the exact same issue for months now.If this box is greyed out or disabled then you need to reset the Windows Credential Manager first.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).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.In fact if you just turned on MFA and you were not using MFA before you usually end up having to rebuild the profile and clearing the credential manager.This is now the 2nd machine that presents the same issue.
When we opened the old, existing profile it didn’t ask for ANY authentication, it just started working. Modifying the Outlook profile by using the "Profiles" registry path is not supported and may cause your Outlook profile to be in an unsupported state. Troubleshoot Office 365 Sync and Login Issues Serious problems might occur if you modify the registry incorrectly. Before you access it, back up the registry for restoration in case problems occur. We are looking at using conditional access policies where a user with a Domain joined PC is not prompted for MFA.
Outlook stuck in an MFA loop
I do NOT have this issue with the other laptop, an iPad, a MacBook Pro and connection status shows disconnected tablet. 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.
Outlook 365 Password Prompt Issue on Windows Desktop
So not doing anything at all even seems to work. Which to me sounds Exchange connectivity diagnostic like the issue is service side, not client side. 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.