Teams Personal Account Showing as “Unknown User”

The "Unknown User" issue is expected to be solved with the latest Teams 26106 update.

https://status.cloud.microsoft/m365

Just to avoid any confusion, please check the email address you are using with your Microsoft account. It appears that there is no Microsoft account with the email address you have provided in your original post.

However, if outlook.com is replaced with hotmail.com, then such Microsoft account exists.

The behavior where an account shows as Unknown User is expected in specific situations in Teams and is usually related to how the identity is provisioned and cached.

From the documented behavior:

1. Unknown User behavior
   • Deleted user accounts, and disabled-then-reenabled accounts, appear as Unknown User in Teams.
   • When a disabled account is re-enabled, the Unknown User display can persist for up to about two weeks before updating automatically.
   • Display name and other user attributes are also cached by the Teams service and client for several days (up to 3 days in the service, and up to 28 days in the client for some attributes).
   Although the documentation explicitly calls out organizational accounts, the same underlying caching and identity-refresh behavior can cause a newly created account to temporarily appear as Unknown User until the identity fully propagates and caches refresh.
2. Chats between personal and organizational accounts
   When chats involve personal accounts and work/school (organization) accounts, policies and technical limitations can cause some users to display as Unknown or Anonymous, and can also affect the ability to accept or continue chats. Organizations must explicitly allow chats with personal users, and their policies can block or remove personal users or cause them to appear as Unknown.
3. What can be done from the client side
   Given the documented caching and identity behavior, the following are the only supported client-side actions:
   • Sign out of Teams in the browser and sign back in after some time to force a refresh of cached identity data.
   • Allow time for identity and profile information to propagate and for Teams caches (service and client) to update. This can take up to several days in some cases.
   There is no documented client-side method to directly “unstick” or re-provision a Teams personal identity when it is showing as Unknown User immediately after creation.
4. Next step: contact support
   Because this started immediately after account creation, persists across sign-out/sign-in, and is blocking acceptance of chat requests with an error (“Something went wrong. Please try again.”), this aligns with a backend provisioning or service issue rather than a configuration that can be fixed from the browser. The recommended next step is to contact Microsoft support for Teams Free/Teams personal and provide:
   • The affected Outlook.com address.
   • The time the account was created.
   • A description of the symptoms (Unknown User / @invalid.teams.ms identity and the error when accepting chat requests).
   Support can check whether the Teams chat identity provisioning for the personal account is incomplete or stuck and correct it on the service side.

References:

• User appears as Unknown User in Teams
• Why are some features not available in chat in Microsoft Teams Free?
• User information isn't updated in Teams