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Sayali-MSFT's avatar
Sayali-MSFT
Icon for Microsoft rankMicrosoft
Sep 05, 2025

Hello @Benjiiim -Listing installed apps in a chat (GET /chats/{chat-id}/installedApps) works for group chats and 1:1 chats. For meeting chats (chats created for online meetings), this API is not fully supported for all tenants and scenarios. The 404 error with UnknownError is a common symptom when the API is not supported for the chat type or the app context.

Meeting chats are a special type of chat in Teams, and the Graph API support for listing or adding apps to these chats is limited and sometimes only available for certain Microsoft-internal or preview tenants.

There is no supported workaround to list or add apps to a meeting chat via Microsoft Graph in most production/dev tenants.If you need to automate app installation for meetings, this is not currently possible via Graph API.



Benjiiim's avatar
Benjiiim
MCT
Sep 06, 2025

Hello Sayali-MSFT​ 

Thanks for your quick answer and these insights.

Would you mind sharing an official documentation mentioning this restriction or improve the official documentation to mention this?

All the related pages from the Microsoft Graph documentation says things like "Note: If the chat is associated with an onlineMeeting instance, then, effectively, the teamsApps installed in the meeting will be listed."
18 occurences of this note according to a GitHub Code search and nothing explaining that this is only available to Microsoft-internal or preview tenants.

Furthermore, there is a 4 years old article in the official Microsoft Azure Medium blog, written by a Software Engineer at Microsoft explaining how you can add an app to a Teams meeting using these APIs: Adding Custom App to Microsoft Teams Meeting Using Microsoft Graph APIs. | by Manish Saluja | Microsoft Azure | Medium. How can this article have been up for so long if these APIs are not really available?

Can you share the plans around these APIs to make them available for external developers?

Thanks again

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