Teams issues (unknown User)

Question

Hello

Please i need your help on this issue

We have an issue where certain users appear as “Unknown” or “Unverified” in Teams chat. This happens inconsistently — different users may appear unknown after signing out and back in.

The issue occurs in both desktop and web clients, and affected users are all active, known, and were recently contacted.

Steps already taken to troubleshoot:

1. Verified all affected users exist in the tenant and have not been deleted or renamed.
2. Tested in incognito/private mode on web — issue persists.
3. Confirmed network connectivity to Teams endpoints.
4. Cleared Teams desktop cache: Deleted %APPDATA%\Microsoft\Teams\Application Cache\Cache Deleted %APPDATA%\Microsoft\Teams\blob_storage Deleted %APPDATA%\Microsoft\Teams\Cache Deleted %APPDATA%\Microsoft\Teams\databases Deleted %APPDATA%\Microsoft\Teams\GPUCache Deleted %APPDATA%\Microsoft\Teams\IndexedDB Deleted %APPDATA%\Microsoft\Teams\Local Storage Deleted

Answer 1

Hi @Rita Rita,

Thank you for posting your question to Microsoft Q&A Forum.

Unknown users in Microsoft Teams often appear due to guest access misconfigurations, where external identities aren’t captured correctly. They can also result from mismatched accounts, such as using a personal Microsoft account instead of a work email. Poor connectivity during meetings may temporarily prevent profile data from loading, while permission changes or account migrations can disrupt identity syncing. Additionally, anonymity settings for privacy and occasional technical glitches, like bugs or updates, can cause known users to display as unknown.

You can try the following steps to see if it works: 

1/ Clear Teams cache: 

Since you're using the cache clearing method for Classic Teams, the directory isn't correct. I'd recommend you delete new Teams cache by following this article: Clear the Teams client cache - Microsoft Teams | Microsoft Learn

2/Sign out User from all Devices

Go to Microsoft 365 Admin Center by visiting admin.microsoft.com and logging in with your administrator credentials.  Left-hand menu, go to “Users” or “Active users.”  Locate the user you wish to sign out from all devices and select them.  Sign out the User from all devices in the Account section.

3/ Check Windows update

Open Settings. Go to Windows Update (lower left portion of Settings page)

Make sure that your Windows is up to date.

If not, click on Check for updates or Download and Install Updates.

4/ Contact Microsoft support team: If the issue persists after you tried the steps above, you can request your IT to raise a support ticket on your behalf. This route ensures that a Microsoft support engineer can initiate a remote session to investigate backend configurations, run advanced diagnostic tools, and, if necessary, escalate the case to specialized teams with access to internal systems and logs. These backend resources are essential for resolving issues that go beyond what’s visible in the user interface.

They can create a support ticket from Microsoft 365 Admin Center > Support > Help & Support.  

Microsoft also provides customer service phone numbers based on your region. You can find the appropriate contact number here: Customer service phone numbers - Microsoft Support 

 

Note: We appreciate your understanding regarding the scope of support available through this forum. As moderators, our role is to provide general guidance and assist with common troubleshooting steps. While we do not have access to internal systems or administrative tools required to resolve account-specific or backend-related issues, but we’ll continue doing our best to support you within the scope of our responsibilities.  

I hope the information provided proves useful. Please proceed with the outlined steps and let me know whether they resolve the issue. If not, I’ll be glad to continue working with you to find a solution.

 

I genuinely appreciate your understanding and patience throughout this process. Should you have any questions or need further assistance, feel free to reach out at any time.

 

I look forward to hearing from you.

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