Yesterday there was the following scenario with a customer.
– User mailboxes were migrated with third party tools to a new Office 365 tenant.
– UserPrincipalName stayed the same.
– Employees used the same laptop and profiles than before.
– Exchange Hybrid was built to manage users.
– AutodiscoverInternalUri was nulled.
When customer started creating new Outlook profiles, there was an error with autodiscover usage. It seemed that it cannot find dns-records, but everything was in-place and created correctly.
ADAL prompt flashed really quickly onscreen and then disappeared.
The reason for this behavior was ADAL and the old identities inside Registry.
Browse to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities and remove all identities.
Or just disable ADAL completely.
Windows Registry Editor Version 5.00
After this You will get Old Sk00l login prompt for Outlook and everything works.