Unable to Access Microsoft Outlook (@lumpkinsinsurance.com)

A Microsoft 365 administrator must assign the affected user a license that includes Exchange Online, because the displayed OwaUserHasNoMailboxAndNoLicenseAssignedException indicates that Outlook on the web cannot find a licensed mailbox for that account.

Assign or correct the Exchange Online license

1. Sign in to the Microsoft 365 admin center with an administrator account.
2. Go to Users → Active users.
3. Select the affected user.
4. Select Licenses and apps.
5. Under Licenses, assign a product containing Exchange Online.
6. Expand Apps and ensure the Exchange Online service is enabled.
7. Select Save changes. These are Microsoft’s documented license-assignment steps.^1^

If no license is available, an administrator must purchase another license or free one from a user who no longer requires it. Do not merely assign desktop Office applications—the assigned product must include Exchange Online.

If the Exchange license was recently removed or expired, reassign it promptly. For a regular mailbox without a hold, Exchange Online disconnects the mailbox when its license is removed; reassignment within 30 days reconnects it, while after 30 days the mailbox is permanently deleted and unrecoverable.^2^

Allow provisioning to complete

After assigning the license:

1. Wait at least 30 minutes.
2. Sign out of Microsoft 365 completely, close the browser, and sign in again.
3. Test Outlook on the web.
4. In the admin center, confirm that the user now appears under Exchange admin center → Recipients → Mailboxes.

Mailbox provisioning and license changes usually complete in less than 30 minutes but can take up to 24 hours.^3^

If the license already shows as assigned but no mailbox appears:

1. Run the mailbox-provisioning diagnostic linked from the Microsoft 365 admin center guidance.
2. Check the user record for license or validation errors and resolve any displayed issue.
3. Go to Health → Service health and check for an Exchange Online incident affecting the tenant.
4. If licensing is group-based, verify that the user has actually inherited the license and that no assignment error is displayed.

Do not remove and reassign a currently valid license merely as a routine first step, because removing it disconnects a regular mailbox. Use the provisioning diagnostic and inspect assignment errors first.

Escalate if it remains unavailable

If the mailbox still has not appeared after 24 hours:

1. In the Microsoft 365 admin center, select Help & support.
2. Enter the exception name: Microsoft.Exchange.Clients.Owa2.Server.Core.OwaUserHasNoMailboxAndNoLicenseAssignedException
3. Include the UTC timestamp, request ID, and affected account—but do not post those identifiers publicly.
4. If automated results do not resolve it, select Contact Support and choose phone or email.

An administrator can open the service request when the subscription was purchased directly from Microsoft; if all subscriptions were purchased through a partner, contact that partner instead.^4^

Clearing browser data is unlikely to address this particular error because the page identifies a server-side mailbox and licensing condition rather than a browser-session failure. Also remove or mask the organization’s email address/domain and diagnostic identifiers from public posts.

References

1. Assign or unassign licenses for users in the Microsoft 365 admin center
2. Can't access the mailbox of an unlicensed user in Exchange Online
3. Delays in provisioning of user/mailbox or synchronizing changes in Exchange Online
4. Get support for Microsoft 365 for business