modern authentication problems, Windows security and autodiscover pop in outlook 2016 connecting to office365

Benard Mwanza 996 Reputation points
2022-10-26T09:18:32.04+00:00

Recently after Microsoft disabled legacy authentication in office365 our users started experiencing outlook authentication problems.

Issue,
In outlook 2016, a user gets windows security popup windows to key in password, after adding the password, we get another pop up for Autodiscover certificate. What could be the problem and how to resolve it.

Hacks i tried without success.
Removed outlook and office cached credentials in credential manager.
Removed orphaned office registry keys located at HKEY_CURRENT_USER\Software\Microsoft\Office\x.0 and rebooted machine.
Re-installed office again by downloading the file from office 365 profile, still the same issue
When i click view the certificate, the certificate belongs to microsoft as it has all o365 exchange online endpoint in subject alternative name

We are fully cloud office365 org.

see the pop ups
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