Custom connector error log for debugging

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Posted on by YJ-02010636-0

Hi, I’m currently working in Copilot Studio and calling a custom connector API directly (not with Power Automate flows).

I’m encountering errors during the API call, but Copilot Studio only returns a very generic message (e.g. “Error 500", "Error 400") without any detailed logs or response body. This makes it difficult to identify the root cause.

Could you advise on:

How to access full error logs or raw API responses within Copilot Studio?

Whether there is a way to surface detailed error messages from the custom connector (e.g. response body, status code)?

Any best practices for debugging custom connector calls directly inside Copilot Studio?

Would appreciate any guidance on improving observability or debugging in this setup. Thanks!

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Calling actions from Copilot Studio

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MS.Ragavendar 7,162 Super User 2026 Season 1 on at

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@YJ-02010636-0,

You can test your agent in real-time using the activity map in the copilot studio.

https://learn.microsoft.com/en-us/power-platform/release-plan/2025wave1/microsoft-copilot-studio/understand-agents-activity

https://learn.microsoft.com/en-us/microsoft-copilot-studio/authoring-review-activity

✅If this helped, please Accept as Solution to help others ❤️ A Like is appreciated 🏷️ Tag @MS.Ragavendar for follow-ups.

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deepakmehta13a 362 on at

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Hi,

This is a pretty common limitation when working with custom connectors directly in Copilot Studio. I’ve run into the same thing where it only shows generic errors like 400 or 500, without the actual response details.

Right now, Copilot Studio doesn’t expose full request/response logs. To see what’s really happening, it helps to test the connector outside Copilot Studio, either in the custom connector Test tab or through a simple Power Automate flow, where you can see the full outputs in run history.

To improve error visibility, you can:

Return structured JSON responses from your API (even for errors)

Include fields like message, errorCode, etc.

Define proper response schemas in the connector

For debugging, a couple of things that usually work well:

Use a Power Automate flow as a wrapper to capture and return the response

Add logging on the API side (Application Insights, server logs, etc.)

Test the API and connector separately before using it in Copilot

So overall, since logging is limited in Copilot Studio, combining external testing + better API responses is usually the most practical way to debug.

Hope this helps.

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