External users appearing as "Unknown User" in Teams Chat (Desktop, Web and Mobile)

Question

External users appearing as "Unknown User" in Teams Chat (Desktop, Web and Mobile)

Daniel Baxter 46

We use the external access functionality for Teams, to allow our users to speak to users of other specific domains.

Recently, some external users have started to appear as "Unknown User" in our Teams chats, this is on Desktop, Web and Mobile.

The general Teams functionality still works as normal, we can message and call the user.

I have also had it reported from some external users that our internal users are also appearing as "Unknown User" on their side.

All Teams clients are the latest version: You have Microsoft Teams Version 1.6.00.22378 (64-bit). It was last updated on 24/08/2023.

Unknown User

Anyone experienced this before? Know of a fix/workaround?

Thanks

Daniel 35 Reputation points

2023-12-08T03:16:45.0366667+00:00

We are seeing the same issue here, just in recent weeks.

The external accounts show fine in Outlook/SharePoint/365 Admin, but show as 'Unknown User' in Teams. Tried Teams on the Web, Desktop, Classic and New - all with the same result.
Dimitri Baikrich 271 Reputation points

2023-12-08T06:52:18.15+00:00

Hello,
Azure Active Directory has an eventual consistency strategy for replication across the different instances. It might take a few minutes, but I've seen changes that took longer than that to replicate on different regions.

Could it be the case that the user is created just before the meeting and that it had not had the time to propagate to all instances? What happen if you create the user an hour beforehand?
Daniel 35 Reputation points

2023-12-10T22:52:52.8933333+00:00

Unfortunately, I don't think this a replication issue - these accounts were created months ago, and still show as 'Unknown User'
Jack Stedman 10 Reputation points

2023-12-14T11:24:29.7733333+00:00

One of our users is also having this issue. All external attendees in meetings are showing as "Unknown User"
MAIREYThomas 0 Reputation points

2023-12-19T09:27:42.27+00:00

Hello
We are encountering the same issue, some newly contacted external users appear as "unknown user".
Maybe it disappears after a few days ?

2 answers

Your answer

Daniel 35 Reputation points

2023-12-08T03:16:45.0366667+00:00

We are seeing the same issue here, just in recent weeks.

The external accounts show fine in Outlook/SharePoint/365 Admin, but show as 'Unknown User' in Teams. Tried Teams on the Web, Desktop, Classic and New - all with the same result.
Dimitri Baikrich 271 Reputation points

2023-12-08T06:52:18.15+00:00

Hello,
Azure Active Directory has an eventual consistency strategy for replication across the different instances. It might take a few minutes, but I've seen changes that took longer than that to replicate on different regions.

Could it be the case that the user is created just before the meeting and that it had not had the time to propagate to all instances? What happen if you create the user an hour beforehand?
Daniel 35 Reputation points

2023-12-10T22:52:52.8933333+00:00

Unfortunately, I don't think this a replication issue - these accounts were created months ago, and still show as 'Unknown User'
Jack Stedman 10 Reputation points

2023-12-14T11:24:29.7733333+00:00

One of our users is also having this issue. All external attendees in meetings are showing as "Unknown User"
MAIREYThomas 0 Reputation points

2023-12-19T09:27:42.27+00:00

Hello
We are encountering the same issue, some newly contacted external users appear as "unknown user".
Maybe it disappears after a few days ?

Answer 1

JimmyYang-MSFT 58,641 Microsoft External Staff

Hi @Daniel Baxter

Does this issue persist all the time?

As regards to the co-existence mode, is it different from the other users in your organization?

For current situation, please try following the steps below and see how it goes:

Sign out and then quit the Teams desktop client.
Navigate to C:\Users<UserName>\AppData\Roaming\Microsoft\Teams
(Note: The AppData folder may be hidden, in this case, please go to View on the ribbon, then tick the "Show Hidden folders" box.)
Delete all the content from this folder.
Restart Microsoft Teams.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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Daniel 35 Reputation points

2023-12-08T03:18:53.0366667+00:00

Issue happens in Teams on Web, so isn't a caching issue.
Brian Burns 5 Reputation points

2024-01-22T21:04:55.16+00:00

This worked for me!!! I checked with Team online and notice the username was still correct. It was only shown as unknown user for my desktop version of teams. Once I went thru the steps above, it was fixed. Thank you.
Daniel 35 Reputation points

2024-01-22T23:32:21.46+00:00

We ended up contacting Microsoft support and they ran a manual sync in the background between Teams and Azure AD, which fixed this issue for us.
Kim, Bum-Soo (CSWind) 25 Reputation points

2024-01-29T08:45:04.68+00:00

Hello Mr. Daniel I've been experiencing a similar issue lately. I have previously completed testing through my personal account. I changed the External users to Guest users by adding them as Guest in Azure Admin center. However, no matter how many times I repeat it, the users I added today still appear as External users and I can't find a way to synchronize them. If you don't mind, Could you let me know how to synchronize them?
MRotta 5 Reputation points

2024-03-21T18:38:15.0866667+00:00

Worked for me as well.
Gagne-Richard, Martin 5 Reputation points

2024-03-27T18:49:42.77+00:00

My organisation is using E5 licence, our MS Teams cache isn't in AppData/Roaming but in Packages repo : C:\Users<username>\AppData\Local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache
If it can helps someone. After deleting files in this LocalCache folder on the client PC (person who see the Unknown User), correct name is back to normal in Teams.
yos 0 Reputation points

2024-06-19T08:27:47.9+00:00

Hi Daniel,

Could you please explain the process to solved the problem?

Regards

Yosef
Oleksandr Ridkodub 0 Reputation points

2024-08-28T06:31:26.08+00:00

We are encountering the same issue with Microsoft Teams that is impacting on our ability to collaborate with our partner organization.
It would be really helpful if Microsoft could share the steps to perform this synchronization between Entra ID and Teams, as the issue still persists.
Abhimanyu Sharma 86 Reputation points

2024-10-07T13:25:46.9166667+00:00

@Brian Burns, can you please do share the steps here again, if possible, we're experiencing the same issue.

Answer 2

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External users appearing as "Unknown User" in Teams Chat (Desktop, Web and Mobile)

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