Conversation not found error when testing LangChain Sample Agent - Node. js in Agents Playground

[garrytrinder]

Describe the bug
When testing the LangChain Sample Agent - Node.js in Agents Playground, after sending the first prompt ("What can you do?"), the agent fails to respond and multiple errors are logged:

• Conversation not found errors from agents-playground-server (statusCode: 404)
• connect ECONNREFUSED 127.0.0. 1:3978 InternalServiceError when attempting to communicate with the Bot Framework endpoint
• Timed out waiting for: http://127. 0.0.1:3978/api/messages; exiting with error

To Reproduce

1. Launch Agents Playground and select the LangChain Sample Agent - Node.js sample.
2. Send the prompt: What can you do?
3. Observe the error logs and lack of agent response.

Expected behavior
The agent should respond to the prompt, establishing and maintaining the Bot Framework conversation successfully.

Screenshots and Logs

debug Telemetry: agents-playground-cli/cliStart {"cleanProperties":{"isExec":"true","argv":"<REDACTED: user-file-path>/bin/agentsplayground"}}
...
debug Telemetry: agents-playground-server/error {"cleanProperties":{"stack":"Error: Conversation not found...","message":"Conversation not found","code":"ConversationNotFound"}}
... 
log InternalServiceError: connect ECONNREFUSED 127. 0.0.1:3978
	at exports.UserBotError (/Users/garrytrinder/.nvm/versions/node/v22.20.0/lib/node_modules/@microsoft/m365agentsplayground/dist/index.js:2:1235972)
... 

Environment (please complete the following information):

• OS: macOS 15.7.2
• Node Version: 22
• Agents Playground CLI version: 0.2.20

Additional context

• It appears the agent is not establishing or maintaining a valid Bot Framework conversation when run locally, causing errors and agent non-response.

[garrytrinder]

Turns out that when running npm run dev the server was not being started.

I was able to fix this by adjusting the dev script in package.json.

    "dev": "nodemon --watch src --exec ts-node src/index.ts",

[pontemonti]

Hi @garrytrinder , thanks for reporting this issue. I have tried to reproduce it. The only thing that I noticed when trying to start the latest version was that it didn't build cleanly so I created #111 to address that.

The difference between the current npm run dev and the change you shared is that the --watch parameter is set to src instead of src/*.ts - that shouldn't result in the server not starting. Could you confirm this by changing the value back?

[garrytrinder]

I'm on node v22.20.0 and macOS.

[pontemonti]

@garrytrinder - thanks, looks like something that works on Windows but not MacOS. The suggested change still works on Windows so we could make this change.