Timeout error when starting new conversation in Copilot M365 when using "(Preview) Debug in Copilot (Edge)"

[Entouanes]

Describe the bug
I created a "Basic Custom Engine Agent" template. When running "(Preview) Debug in Copilot (Edge)", the agent is successfully provisioned and deployed, and it appears in the Copilot M365 interface.
However, when creating a new conversation with the agent, a timeout error occurs and the agent returns:

"Sorry, something went wrong. I am unable to give you this response at the moment. I will keep working on your query and respond later."

If I refresh and access the conversation from the left tab, the conversation then appears successful.
See the attached screenshot 1, 2 for illustration.
Output from the Microsoft 365 Agent Toolkit in VSCode shows an error "... error: connect ECONNREFUSED 127.0.0.1:9222", see screenshot 3

To Reproduce
Steps to reproduce the behavior:

1. Create a "Basic Custom Engine Agent" template.
2. Run "(Preview) Debug in Copilot (Edge)" to provision and deploy the agent. (Screenshot 3)
3. Open Copilot M365 and start a new conversation with the agent.
4. Observe the timeout error. (Screenshot 1)
5. Refresh and access the conversation from the left tab to see the successful response. (Screenshot 2)

Expected behavior
The agent should respond successfully when starting a new conversation, without any timeout error.

Screenshots
(1)

(2)

(3)

VS Code Extension Information (please complete the following information):

• OS: Windows Subsystem for Linux (WSL)
• VSCode Version: 1.101.2
• Extension: Microsoft 365 agents toolkit 6.0.1

CLI Information (please complete the following information):

• OS: Windows Subsystem for Linux (WSL)
• Version: [please specify if different from above]

Additional context
Let me know if you need any more logs or details.

[m365-agent-toolkit-assistant]

👋 Hi @Entouanes,

Thank you for reporting this issue! We want to let you know that:

⏱️ Our team will personally review your issue
🎯 You can expect a response within 2 business days

✨ This is an AI-generated initial response
🤖 AI-Generated Preliminary Analysis:

This "timeout error" when starting a new conversation is a known issue when debugging agents via "(Preview) Debug in Copilot (Edge)", especially with errors like ECONNREFUSED 127.0.0.1:9222 or initial API tunnel timeouts.

Root causes and workarounds:

• The issue often occurs due to local DevTunnel startup latency or tunneling not being ready on first request (details).
• Sometimes, user/tenant licensing affects response visibility (details)—ensure you have Copilot access or metering enabled.

Actionable steps:

1. If you’re using DevTunnel, try manually starting the tunnel via CLI and setting the URL in your .env file (OPENAPI_SERVER_URL).
2. Refreshing the chat tab can "warm up" the tunnel and allows subsequent messages to succeed.
3. Always clear cached DevTunnel URLs between sessions.

These workarounds help while Microsoft continues upgrading the toolkit’s tunneling support. For more context and latest updates, monitor issue #12691.

✨We'd love your feedback! Please take a moment to fill out our survey.

---

Note: This is an automated first response generated by AI. A human team member will review your issue and provide a more detailed response soon. We appreciate your patience!

[frankqianms]

Thank you @Entouanes for raising the issue. We will look into this timeout issue for the root cause and give you response soon.

[frankqianms]

@Entouanes What programming language did you choose?

After some tries, we couldn't reproduce the issue. Maybe it's an occasional issue that the response was timeout. Did you encounter it every time you debug in Copilot?

As for error in screenshot 3, I believe that's because you refreshed the browser so that the VS Code debugger lost connection to the remote debug interface on port 9222.

[Entouanes]

Thank you @frankqianms I am using the "Weatherbot" template, in Typescript.

I have encountered this issue everytime I debug in Copilot.

I will try on different network(s) to see if it plays a role.

[frankqianms]

Hi @Entouanes~ Did you try different network, and did it work to you?