Group Chat with Externals issue

Question

Group Chat with Externals issue

Connor 25

We are in a Cross Tenant Sync with another company - this happens in our home tenant.

We had a group chat that we added 9 people from the other company. It was working fine, then all of a sudden it kicked all externals.

We now can't add the externals back to the group chat.

The "Learn More" on the error points to Teams for Education & Supervised Chats. We are not using supervised chats or Teams for Education. We use Teams for Business

User's image

0 comments

1 answer

Your answer

Answer 1

Darren-Ng 12,765 Microsoft External Staff Moderator

Dear @Connor,

Thank you for posting your question in the Microsoft Q&A forum.

Based on your description, your Teams group chat previously worked with cross-tenant synchronized external users, but all external participants were removed and can no longer be added back, displaying the error "You don't have permissions to add certain people to the chat."

This issue is more likely related to Cross-Tenant Access or Teams External Access configuration rather than Teams for Education or Supervised Chats.

For better understanding your situation, could you please help confirm the following:

Can you create a new group chat and successfully add the affected external users?
Does the issue affect all external users from the partner organization or only specific users?
Can affected users still communicate through 1:1 Teams chats with users in your tenant?

In the meantime, as an initial troubleshooting step, I recommend that both tenant administrators review the Cross-Tenant Access settings and Teams External Access configuration to ensure collaboration between the two organizations is still allowed. A policy change on either tenant may prevent external participants from being added to existing chat.

Additionally, please test whether the affected users can be added to a new group chat. If a new chat works correctly, the issue may be related to the original chat thread. If the problem occurs in all chats, it would point more toward a tenant-level configuration issue.

Here are some articles that you may refer to

Manage cross-tenant access settings for B2B collaboration

Overview: Cross-tenant access with Microsoft Entra External ID

Looking forward to your update.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Connor 25 Reputation points

2026-07-23T00:54:25.1166667+00:00

Hi Darren,

I can confirm that we can create a new group chat and add an affected external user.

We can communicate through 1:1 Teams chats with all affected users fine
It seems to be all external communications are working; other group chats are working.

I have checked all policies and external sharing are the same and set to allow access, thus other Chats ETC working.

It is just this group chat affected. We tried to add another external (that wasn't originally in the group chat) and it error'd out the exact same.

It seems to be only this specific Microsoft Teams GroupChat
Darren-Ng 12,765 Reputation points Microsoft External Staff Moderator

2026-07-23T03:06:02.9+00:00

Hello,

Thank you for your update,

This significantly reduces the likelihood of a tenant-level configuration issue and suggests that the problem may be isolated to the specific Teams chat thread itself. As a further test, could you confirm whether the issue occurs regardless of which internal user attempts to add the external participant to the affected chat? If multiple internal members receive the same error and all other external collaboration scenarios continue to work, the evidence points to a problem with the chat object's backend state rather than Cross-Tenant Access or Teams External Access settings.

As a workaround, you may consider creating a new group chat and re-adding the participants. If retaining the original chat is important for business purposes, I recommend opening a support case with Microsoft Support so the Teams service team can investigate the affected chat thread from the backend, as this type of issue is generally not visible through Teams Admin Center settings.

If you are an admin, you can use this link to find the appropriate contact number: Global Customer Service phone numbers - Microsoft Support

Or you can submit ticket support in the Microsoft 365 Admin Center https://admin.microsoft.com/#/support/requests > Support > Help & Support.

The Microsoft Online Support Team has higher permission than me moderator to remotely assist you and collect background logs for the root cause.