Outlook on prem prompts for O365 Password
Issue: In an Exchange on prem environment Outlook prompts for O365 Password trying to connect to exchange online or Office365. and is not connecting after that. Cause: Moder authentication was enabled Solution: First, we thought of postponing the O365 request, by adding registry Dword (ExcludeExplicitO365Endpoint) this will tell Outlook to postpone the O365 Autodiscover request to the last. 1- Open Registry Editor 2- Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Office\<x.0>\Outlook\AutoDiscover 3- 3- 3- Create new Dword : ExcludeExplicitO365Endpoint value 1 but this didn't solve the issue so we decided to disable Modern authentication 1- Open Registry Editor 2- Navigate to: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\<x.0>\Common\Identity 3- Create Dword: EnableADAL value 0 DisableAADWAM value 1 DisableADALatopWAMOverride value 1 then the Prompt stopped and outlook connected to On-prem Autodiscover