Outlook 2016 Keeps Prompting for Password
Following the May Windows and Office updates we’ve seen a massive number of issues with clients losing internet connectivity and Outlook messing about.
The most recent issues is where Outlook keeps prompting for a Password and it appears to happen after the user changes it and if the tenant is enabled for Multi Factor Authentication (MFA)
Any clients which have exhibited this behaviour the only fix has been to implement the following registry key and disable modern authentication.
Create the following registry key as a DWORD 32 bit and set the value to 0.
Open outlook and you should be able to enter the password as normal.
Hopefully the cause will become clear over the next few days or at least Microsoft with patch the problem and you can then delete the registry key.