Office 365 Hybrid Constant Credential Prompts

When an Exchange users is migrated to Office 365 they may get constant credential prompts. Even if the user enters the correct credentials the prompt will come back in a few minutes. The user might also lose the ability to access shared mailboxes and public folders. 

The fix is to set all of the reg keys below to 1, doing so will enable modern authentication.

Office 2013:

Office 2016:

All versions 2013+ Create this even if you are on 2016 where it is enabled by default

Restart Outlook and the prompts should go away. 


  1. this is really a good informative website i have ever every seen. i have got a lot of good knowledge from
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  2. An Office 365 migration everything over in batches. It transitions all of your resource mailboxes and existing users from One Office 365 tenant to another... During the migration, Office 365 users will still have the ability to send and receive emails from users that haven't migrated over yet.


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