I have seen many reports of Outlook 2016 – Office 365 asking for a password. The user enters their email address using Microsoft’s “Modern Authentication”, but the next screen asking for the password disappears. This of course prevents the user from authenticating to the Office 365 Exchange servers.
Close all Microsoft Office applications.
Turn off the modern authentication by adding the following DWORD (32) to the registry:
Make sure the value is set to 0 (zero). It should default to this value.
Restart the offending Microsoft Office application, Outlook is generally where the issue is most prevalent. You will then get the legacy authentication prompt, similar to the below image.
This article is intended for advanced users and/or I.T. professionals. Modifying the registry can cause your computer to become inoperable.
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