Exchange Connection Problems

Fix Outlook UserHasNoMailboxAndNoLicenseAssignedException

Maira Mehtab Sep 20, 2026 868 views

Question details

An Outlook domain account was unexpectedly removed and cannot be re-added due to a specific mailbox and license exception error.

Product: Microsoft Outlook
Device & OS: not provided
Scenario: Attempting to re-add a removed domain account into the Outlook desktop client.
Observed behavior: Outlook refuses to add the account and displays the error UserHasNoMailboxAndNoLicenseAssignedException, even though other accounts continue to work properly.

Before you start

You will need access to the Microsoft 365 Admin Center with Global Administrator privileges, or you must contact your organization's IT admin to perform these checks.

Solution 1Recommended

Verify and Reassign the Exchange Online License

Check if the user has a valid Exchange Online license assigned, and toggle it to force a backend refresh of the mailbox.

Often, a synchronization glitch in Microsoft 365 can cause the system to temporarily lose track of a user's license, triggering this exception in Outlook. Unassigning and reassigning the license can force the server to re-provision the mailbox state.

Access Microsoft 365 Admin Center

Locate the User

Navigate to Users > Active users in the left menu and click on the affected user's account.

Check Licenses and Apps

Select the 'Licenses and apps' tab to ensure a license plan containing Exchange Online is currently active.

Unassign and Reassign

Uncheck the assigned license, save the changes, wait a few moments, and then recheck the license to assign it back. Save the changes again.

Propagation Time: It may take anywhere from 15 minutes to a few hours for the reassigned license to propagate across the Exchange servers before the user can successfully sign in to Outlook again.

Solution 2

Open a Microsoft Support Request

If the license is correctly assigned but the error persists, Microsoft support must investigate the backend issue.

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Frequently Asked Questions

What does the UserHasNoMailboxAndNoLicenseAssignedException error mean?

This error means the Exchange server cannot find a valid Exchange Online license or an active mailbox associated with the user account you are trying to add to the Outlook client.

Why did my Outlook account get removed suddenly?

The account may have been automatically removed or disconnected if the Outlook client detected a sudden loss of connection to the mailbox, which is often caused by a temporary backend licensing glitch or an expired subscription.

Can the user fix this error themselves?

No, because this is a server-side licensing and mailbox provisioning issue, the user must contact their organization's Microsoft 365 Global Administrator to check the license assignment or to contact Microsoft Support.

Outlook & Email Problems