Accessing Outlook on the web for business using organizational credentials.
The error OwaUserHasNoMailboxAndNoLicenseAssignedException means the work account can sign in, but Exchange Online does not see a mailbox or the required license assigned. This must be fixed by the organization’s Microsoft 365/Exchange administrator; it cannot be fixed from the user side.
Actions the tenant administrator needs to take:
- Verify a mailbox exists
- In the Microsoft 365 admin/Exchange admin tools, check whether the user has an Exchange Online mailbox.
- If the mailbox is missing or disabled, create or re‑enable the mailbox for the user.
- Verify license assignment
- Confirm the user has an appropriate Microsoft 365 license that includes Exchange Online assigned and active.
- If no such license is assigned, assign one and wait for provisioning to complete.
- Re-test sign-in
- After the mailbox is created/re-enabled and the license is correctly assigned, sign out of all Microsoft sessions, close the browser, then sign back in to Outlook on the web and try again.
If the organization’s IT department cannot resolve this, they need to open a support case with Microsoft 365 support from the Microsoft 365 admin portal so Microsoft can check the tenant configuration and mailbox state.
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