


We ended up having to delete the entire HKCU/Software/Microsoft/Office/16.0/Outlook key from the registry to fix this. All of our Windows 10 users upon restart of their computers were prompted for a password on the standard Outlook username and password dialog and refused to accept the correct password.This failed miserably for us in two parts: A recap of the steps as I understand them: 1) Turn off Legacy per-user MFA, 2) From Azure Admin Center turn on Security Defaults 3) In 365 admin center turn on modern auth under Org settings, 4) have users register devices and continue happily being fully protected.Having heard that MFA was moved to the Azure admin console, I looked for MS current doc on this and found this:.In the past, I used the per-user MFA inside of the Exchange admin console for just administrators. I was setting up MFA for a clients entire tenant.

Answers as I'm getting conflicting information from official MS documentation and a MSO support technician.
