Outlook not opening

Hello Sourav,

Thank you for reaching out to the Microsoft Q&A Community.

The error OwaUserHasNoMailboxAndNoLicenseAssignedException usually indicates that an Exchange Online license is missing or the mailbox is unavailable. Since checking these settings requires administrator permissions, please contact your organization's IT administrator and ask them to:

1. Check the subscription status under Microsoft 365 Admin Center > Billing > Your products.
2. Verify your Exchange Online license under Users > Active users > Licenses and apps. If necessary, carefully unassign and reassign the license, then ensure the Exchange Online service is enabled under Apps. 3. Confirm that your mailbox exists under Exchange Admin Center > Recipients > Mailboxes.

If the issue persists, your administrator can raise a support request through Microsoft 365 Admin Center > Help & support.

Could you also confirm whether Outlook was working previously or if this is your first time accessing it?

Best regards.

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