Why does sending messages with the Microsoft Teams API fail with “conversation not found”?

Question

Why does sending messages with the Microsoft Teams API fail with “conversation not found”?

Schenck Shay 100

When I’m trying to send messages to a Microsoft Teams chat or channel using the Teams API, but the request fails with a “conversation not found”. This happens even though the bot or app is installed and the conversation ID was previously working. How can I deal with it

Sayali-MSFT 6,481 Reputation points Microsoft External Staff Moderator

2026-02-03T05:11:28.34+00:00

Hello Schenck Shay ,Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.
Sayali-MSFT 6,481 Reputation points Microsoft External Staff Moderator

2026-02-03T06:14:01.3466667+00:00

Hello Schenck Shay,
"ConversationNotFound" means the conversation ID is invalid. In general, the error "Conversation not found" happens when the conversation doesn't exist or has been deleted. Which means Some user operations, such as blocking the bot or deleting the bot, may impact that ID.

We already raised the bug for the same. We will let you know once we have any update.

Answer accepted by question author

0 additional answers

Your answer

Sayali-MSFT 6,481 Reputation points Microsoft External Staff Moderator

2026-02-03T05:11:28.34+00:00

Hello Schenck Shay ,Thank you for bringing this issue to our attention. We will look into it and get back to you shortly.
Sayali-MSFT 6,481 Reputation points Microsoft External Staff Moderator

2026-02-03T06:14:01.3466667+00:00

Hello Schenck Shay,
"ConversationNotFound" means the conversation ID is invalid. In general, the error "Conversation not found" happens when the conversation doesn't exist or has been deleted. Which means Some user operations, such as blocking the bot or deleting the bot, may impact that ID.

We already raised the bug for the same. We will let you know once we have any update.

Answer 1

Hi Schenck Shay

Thank you for reaching out to Microsoft Q&A forum

The “ConversationNotFound” error indicates that the Teams Bot Framework (Connector) can’t locate a conversation for the conversationId you are calling.

Given this, you can try these below approaches to see if it can help you

Validate you’re using the correct conversation context for the API you’re calling, ensure the conversationId and serviceUrl come from the bot activity context
For proactive scenarios, follow the supported proactive messaging pattern ensure the app/bot is installed in the target scope (team/channel/group chat) so it has access to message there.
Handing ConversationNotFound by re-establishing context, treat it as a signal that the stored conversation reference is no longer valid. A common mitigation is to re-acquire a fresh conversation context, then update your stored conversationId/serviceUrl and retry.

You can read these documents for more insight:

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

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.

Steven-N 25,315 Reputation points Microsoft External Staff Moderator

2026-02-03T07:54:59.91+00:00

Hi Schenck Shay

It has been a while and I am writing to see how things are going with this issue.

Have you had a chance to check the replies provided?

Any update would be appreciated.