Power Platform Community Forum Thread Details

Question / Description

I’m seeing a consistent difference in error handling behavior in Copilot Studio depending on how a connector is invoked, and I’d like to understand whether this is by design or a limitation.

Scenario 1 – Connector called directly from a Topic

Topic invokes a Custom Connector action directly
Connector returns:
- 4xx / 5xx with body OR
- runtime failure
Result:
- The “On error” branch of the action is triggered correctly
- Topic can handle the error
✅ This works as expected.

Scenario 2 – Tool called from a Topic (Tool wraps the same connector)

Topic invokes a Tool
Tool internally calls the same Custom Connector
Tool error handling is set to “Raise an error”
Connector returns the same error response as Scenario 1

❌ Result:

The Topic does NOT receive the error
The “On error” branch is never triggered
Topic execution does not regain control

Scenario 3 – Agent calls the Tool directly (no Topic)

Agent invokes the Tool directly
Connector returns error

✅ Result:

Agent is able to handle the error
Error behavior works as expected

Observation

It appears that:

Errors raised by Tools invoked from Topics do not propagate back to the Topic runtime
Errors raised by Connectors invoked directly from Topics do propagate
Errors raised by Tools invoked directly by the Agent propagate correctly

Question

Is this difference in error propagation by design?
Are Topics unable to handle errors raised by Tools?
Is there any supported way for a Topic to catch or branch on Tool errors?
Is this documented anywhere, or planned to change?

Categories:

Topic creation & management

Your observations are accurate and reflect a current limitation in Copilot Studio’s error propagation model:

Direct Connector Call from Topic:
Errors (4xx/5xx or runtime) are surfaced to the Topic, and the “On error” branch is triggered.
✅ Expected and documented behavior.

Tool Called from Topic (Tool wraps Connector):
Errors raised by the Tool (even with “Raise an error” set) do not propagate to the Topic’s “On error” branch.
The Topic does not regain control or branch on the error.
❌ This is a known limitation.

Agent Calls Tool Directly:
Errors are surfaced to the Agent, which can handle them.
✅ Expected behavior.

Is This By Design?

Yes, this is by design (as of current Copilot Studio architecture).
Tools are treated as atomic operations when invoked from Topics; their internal errors are not surfaced to the Topic runtime.
Only direct connector actions within Topics can trigger the “On error” branch.

Can Topics Handle Tool Errors?

No, not natively.
There is currently no supported way for a Topic to catch or branch on errors raised by Tools.
The only workaround is to avoid wrapping critical connector calls in Tools if you need Topic-level error handling.

Documentation & Roadmap

This behavior is not well documented in public Microsoft docs as of January 2026.
It is a common source of confusion and has been raised as feedback by the community.
Microsoft may address this in future updates, but there is no official announcement or timeline for changing this behavior.

In summary:
This is a current limitation/by design. Topics cannot catch errors from Tools. Only direct connector actions support Topic-level error handling. There is no official workaround or documentation, but this may change in future Copilot Studio releases.