Can't Open Outlook on Web after changing Primary Username in Admin Center

Copper Contributor

After changing primary username. I'm unable to use Outlook on Web. It will just keeps on asking account to sign-in, after choosing the new username account and login it will return to the same page asking what account to sign-in, stuck in loop unable to proceed to Outlook on Web. OneDrive,Teams,SPO working fine just the Outlook on Web stuck unable to use it. Tried In private, clear cache and cookies still unable to proceed to Outlook on Web.

3 Replies

Hi @Anos_Voldi,

When you make changes to the primary username in the Admin Center, it's crucial to double-check that the new primary email address has been accurately updated. Any errors or typos in the email address can lead to difficulties in accessing Outlook on the web.

Check the primary email address associated with the user's account. Verify that it matches the new username precisely, including any domain or email suffix (e.g.,

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Kindest regards,

Leon Pavesic


Just for general consumption, I have had the same problem with a business account where I set up new User accounts and then completed the DNS and domain set up.  All the information was verified and it let me log in and set up MFA.  However, Iogging into  Outlook presented the same problem as @Anos_Voldi described.  On contacting Microsoft support they confirmed that this is also caused by a known problem with the O365 platform.   A diagnostics process needs to be run which apparently resolves the issue. 

@IT_for_the_communitywhat "diagnostic process"?  Is this something that MS Support must do, or is it self service?  Any hints on how to proceed?