Copilot Studio agent - Persistent SystemError, Teams channel only (OK in Cop. Studio Activity log)

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Posted on by MM-18031933-0

ENVIRONMENT
- Product: Microsoft Copilot Studio
- Channel affected: Microsoft Teams
- Channels NOT affected: copilot.microsoft.com, Copilot Studio test panel

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ISSUE DESCRIPTION

After publishing the agent to the Teams channel, the bot works correctly for a period of time. Then, at some point during usage, every message returns the following error regardless of the question asked:

"Sorry, something unexpected happened. We're looking into it. Error code: SystemError. Conversation ID:XXXXXX"

Key observations:
1. The Conversation ID remains IDENTICAL across all subsequent errors, even after clearing chat history, uninstalling/reinstalling the Teams app, and restarting Teams.
2. When inspecting the session in Copilot Studio → Activity → session detail, the agent shows the CORRECT and COMPLETE answer — meaning the agent processed the request successfully, but the response was never delivered to Teams.
3. The error persists indefinitely — it does not resolve by itself, not even the following day.
4. The ONLY workaround is to re-publish the agent from Copilot Studio with the option "Force newer version for persistent channels" enabled.
5. After re-publishing, the bot works correctly again for a period, then the same issue reappears.
6. All connector connections (Dataverse, SharePoint, Excel) show green/healthy status on make.powerapps.com.
7. The issue affects a specific user session — other users may not be affected at the same time.

It seems that the agent processes the request correctly on the Copilot Studio side, but the response delivery to the Teams channel fails silently. The persistent Conversation ID suggests the Teams-side session becomes corrupted and is never regenerated, even after client-side resets.

Why may the Teams session become corrupted and stop working for that Conversation ID?

Thanks!

Categories:

Bot administration

Publish & channel management

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Prasad-MSFT Microsoft Employee on at

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Root Cause:
Based on the observations, the root cause appears to be a persistent Teams conversation session becoming corrupted or stuck. While the agent processes requests successfully in Copilot Studio, the responses are blocked from being delivered to Teams due to this session state issue. This results in the same Conversation ID being reused indefinitely, causing continuous failures for that user session.

Workarounds:

Until a permanent fix is implemented, the following workarounds can help:

Re-publish the agent with “Force newer version” enabled to reset the session binding.

Start a new conversation manually in Teams to bypass the corrupted session.

Minimize long session dependency and complex orchestration to reduce the likelihood of session corruption.

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We want to assure you that we have highlighted this concern and raised a bug with the engineering team. They are aware of the issue and will investigate a proper resolution to prevent Teams sessions from getting stuck in the future.

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deepakmehta13a 369 on at

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Hi,

This behavior is actually consistent with how Teams handles bot conversations and session caching, and it matches what you’re observing.

A few key points:

Persistent conversationId (expected behavior)
In Teams, there is one persistent 1:1 conversation thread per user–bot pair. Clearing chat, reinstalling, etc. does NOT create a new conversationId. So if that session gets into a bad state, it continues to be reused.

Why it works in Copilot Studio but fails in Teams
Since you can see the correct response in Activity logs, the agent is working fine. The issue is happening in the channel delivery layer (Teams), not in your logic or connectors.

Likely cause
This usually points to a stale or corrupted Teams session / channel binding, where:

The bot processes the request

But the response fails to render/send back to Teams

The session never refreshes automatically

Why “Force newer version” fixes it
This forces Teams to rebind the agent to a fresh backend version, effectively resetting the session for that conversationId.

Practical workarounds

Republish with “Force newer version for persistent channels” (as you’re doing)

Ask affected users to start a new chat with the agent from a different context (if possible)

Avoid long-lived idle sessions where possible

Is this expected?
This is a known limitation/behavior with persistent channels like Teams, especially with long-running sessions. It’s not typically caused by your flow, connectors, or configuration.

Hope this helps.

If this helps resolve your issue, please consider marking the response as Verified so it can help others facing a similar scenario.

If you found this helpful, you can also click “Yes” on “Was this reply helpful?” or give it a Like.

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MM-18031933-0 4 on at

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Hi @deepakmehta13, thanks for your answer.

Now I understand the permanent conversation, so that is as it is supposed to be.

However, this "bad state" of the conversation is not something rare... it happens just after a few minutes into the chat with my agent (maybe after 10-15 messages).

So, the whole bot is basically unusable, I would have to continuously "Force newer version for persistent channels"!

Our users only have Teams channel for this use case, so I really can't see a viable workaround here.

So I cannot consider it a "known limitation/behavoir", this is more like a "blocking bug".

I am stuck

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