Teams Unknown User displayed in chat

IBN 4,416

Hello,

I have a user who received a message from an "unknown user " in teams.

I also tried to send a message to the user on teams. But my profile is showing "Unknown User" when user received my message.

I also notice the Co-existence mood for this affected was set to Teams only.

Does anyone have an idea how to resolve this issue?

What may have been the caused?

Please i need your help.

46614262 5 Reputation points

2023-06-01T04:29:57.4366667+00:00

is this for a single user who is appearing on Teams as a unknown user
46614262 5 Reputation points

2023-06-01T04:31:17.51+00:00
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.

This steps have to be done on the affected user whose name is appearing as unknown /else on the other user's machine on which the user is appearing as unknown

1 answer

Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2022-01-07T02:31:44.923+00:00
Hi @IBN ,

From your description, do you mean some internal users are showing as "Unknown User" in the affected user's Teams desktop client?
Is everything all right in Teams on the web?
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.

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IBN 4,416 Reputation points

2022-01-07T09:27:30.577+00:00

Yes the co-existence mode is different from the other users in the organization?

The affected user is on co-existence mode for Teams Only Mode while others are on Island Mode.

I also tried to change the Co-existence mode from Teams Only to Island I got an error that says "This user is hosted in the cloud and needs Teams only mode to assign an instance of TeamsUp grade Policy"

Do you have an idea why I cant change that to Island mode.

I have attached a screen shot of the error message.

Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2022-01-07T10:03:50.883+00:00

Hi @IBN ,

I also tried to change the Co-existence mode from Teams Only to Island I got an error that says "This user is hosted in the cloud and needs Teams only mode to assign an instance of TeamsUp grade Policy"

This is the expected behavior. According to this documentation, "Modes other than Teams Only can only be applied to users homed in Skype for Business Server on-premises". As indicated in the error message, the user is hosted in the cloud rather than in Skype for Business Server on-premises, so modes other than Teams Only cannot be applied to him/her.

The affected user is on co-existence mode for Island Mode while others are on Teams only.

How about try changing the co-existence mode for the affected user to "Teams only" as well?

Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2022-01-11T23:47:54.07+00:00

Hi @IBN ,

Just circling back to follow up with this thread. Should you need more help on this, you can feel free to post back.

IBN 4,416 Reputation points

2022-01-12T08:28:01.517+00:00

Yes the issue is that a particular user has received a Team chat message from an "unknown user " in teams

it seems the message is received from skype for Business. we need to know who has sent the message.

I have attached a screenshot of the Unknown User.

Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2022-01-14T12:01:00.663+00:00

Hi @IBN ,

Has the particular user checked via Teams web client? Does it also shown as "Unknown user" there?
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Teams Unknown User displayed in chat

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