got a error message

Question

UTC Date: 2026-02-19T19:57:54.775Z
Client Id: PII removed
Session Id: PII removed
Client Version: PII removed
BootResult: configuration
Back Filled Errors: Unhandled Rejection: Error: 500:undefined|undefined:undefined
err: Microsoft.Exchange.Clients.Owa2.Server.Core.OwaUserHasNoMailboxAndNoLicenseAssignedException
esrc: StartupData
et: ServerError
estack: Error: 500
    at Object.w [as createStatusErrorMessage] (PII removed)
    at PII removed
st: 500
ehk: X-OWA-Error
efe: PII removed
emsg: UserHasNoMailboxAndNoLicenseAssignedError

Answer 1

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Hi Toika Hudson

Thank you for posting the question.

That OWA 500 error with Microsoft.Exchange.Clients.Owa2.Server.Core.OwaUserHasNoMailboxAndNoLicenseAssignedException / UserHasNoMailboxAndNoLicenseAssignedError is raised when the service can’t associate the signed-in identity with an Exchange mailbox.

Given this, the below instructions might help:

• Kindly assign an Exchange Online–enabled license to the affected user in Microsoft 365 admin center (Users > Active users > Licenses and apps, ensure Exchange Online is included)
• Save changes.

If it ONLY happen in Microsoft Edge:

Set this Edge policy/registry value to stop the Edge-specific false “no mailbox” condition:

AmbientAuthenticationInPrivateModesEnabled value is changed from 1 to 0 under HKEY_LOCAL_MACHINE\ Software\Policies\Microsoft\Edge

Hope my answer will help you.

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Answer 2

The error message you are encountering indicates that the user does not have a mailbox and no license assigned. This is reflected in the specific error: UserHasNoMailboxAndNoLicenseAssignedError.

To resolve this issue, you should verify the following:

1. Mailbox Assignment: Ensure that the user has an active mailbox assigned to their account in Microsoft 365.
2. License Assignment: Check if the user has the appropriate license assigned that includes mailbox access.

If the user is supposed to have a mailbox and a license, you may need to assign these through the Microsoft 365 admin center or contact your administrator for assistance.

Additionally, if you continue to experience issues, consider checking the Microsoft documentation or support for further troubleshooting steps.

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References:

• Error occurs in EMS, EAC, ECP, OWA, or Outlook on the web in Exchange Server 2013 or Exchange Server 2016
• Exchange ActiveSync Returned an HTTP 500 Error
• Resolve free/busy errors
• Operation Error Codes
• Request Service API error codes