Unable to sign in to Microsoft Teams and Outlook

Question

Unable to sign in to Microsoft Teams and Outlook

Татьяна Макарей 0

Hello Microsoft Support,

I’m unable to sign in to Microsoft Teams and Outlook using my work account. I’ve attached screenshots of both error messages.

When I try to sign in to Microsoft Teams, I see the message: “Application ‘Microsoft Teams’ is disabled.” The error details shown on the screenshot are:

Error code: AADSTS700012
Request ID: [Moderator note: Personally Identifiable Information removed]
Correlation ID: [Moderator note: Personally Identifiable Information removed]
Timestamp: 2026-10-19 08:18:14 UTC

When I try to access Outlook, I receive an error indicating that my account has no mailbox and/or no Exchange Online license. The error includes OwaUserHasNoMailboxAndNoLicenseAssignedException and Error 500.

Could you please investigate why these errors occur and advise what needs to be done to restore access to Teams and Outlook? Please also let me know whether the issue could be related to my Microsoft 365 organization, account licensing, or regional availability. My organization is located in Belarus.

Thank you.

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Answer 1

Dear @Татьяна Макарей,

Good day! Welcome to Microsoft Q&A forum!

Based on the information you've shared, the errors you're seeing suggest that the issue is likely related to your organization's Microsoft 365 configuration rather than a problem with the Teams or Outlook applications themselves.

The AADSTS700012 error in Teams indicates that the Microsoft Teams enterprise application is disabled in the Microsoft Entra ID tenant. Microsoft documentation explains that this type of error occurs when the application's service principal has been disabled and may require administrator intervention to re-enable it if that was not intentional.

For reference: Error AADSTS7000112 - Application is disabled

The Outlook error, OwaUserHasNoMailboxAndNoLicenseAssignedException (Error 500), typically indicates that the account either does not have an Exchange Online license assigned or does not currently have an Exchange Online mailbox provisioned. Microsoft has documented similar cases where the issue was traced back to licensing or mailbox assignment changes within the tenant.

For more information: UserHasNoMailboxAndNoLicenseAssignedError

Therefore, If you have contact of your Microsoft 365 administrator (if you don't, (please also kindly reach out to your colleagues, managers, etc. to see if they have the IT department contact), please ask them to verify:

Whether your account has a valid Microsoft 365 license assigned, including an Exchange Online service plan (If an Exchange Online license is already assigned and appears healthy, the administrator may also consider removing the license, waiting for the change to process, and then reassigning it to trigger mailbox provisioning or refresh the service assignment)
Whether an Exchange Online mailbox exists and is properly provisioned for your account
Whether the Microsoft Teams enterprise application is enabled in Microsoft Entra ID and available for user sign-in
Whether any recent licensing, security policy, or application configuration changes were made that could affect your account

Since both errors point to tenant-level configuration and service assignment, reviewing the account's licensing and application settings would be the most important next step.

Kindly let me know when there are updates or if you need further assistance. Any updates you’re able to share would be really helpful.

I'm here and happy to help! Thank you for your kindness and patience!