Power Platform Community Forum Thread Details

MCP Custom Connector Error from Example

I am trying Pujarini Mohaptra's great post about an end-to-end scenario. I am able to get the server deployed and working in Azure per the instructions. I am able to test the SSE endpoint in a browser and get a session ID. However, when I create the custom connector and test it I get the following error: Property "" type mismatch, Expected: "object", Actual: "string".

Has anyone else run into this?

Thanks!
Andrew

Hi @Andrew I've added a Troubleshooting section that might be helpful.
Feel free to check it out here: https://github.com/biswapm/calculator-sse/blob/main/README.md#️-troubleshooting. From the screenshot, it looks like the code may not have deployed correctly as an SSE endpoint.

Troubleshooting

How to Check if Your SSE Server is Running Properly

Follow these steps to verify that your SSE (Server-Sent Events) server is functioning correctly:

Step 1: Browse the SSE Endpoint

Open your browser and navigate to:
- http://localhost:3000/sse (if running locally), or
- Your deployed Azure URL.
Open Developer Tools → Network tab.
Look for an EventStream connection.
Under the Event section, you should see:
- Endpoint: SSE endpoint
- Data: Your Full URI endpoint

Step 2: Test SSE Endpoint via Postman

Copy the Full URI (from the EventStream data).
Use Postman to send a POST request to that URI.

Example URL:

http://calculatormcp-dummyurl.azurewebsites.net/mcpfy/v1/calculatordemo?sessionId=620c84e1-81e2-484d-8737-a7fbc93165b1

Example Request Payload:

{
  "jsonrpc": "2.0",
  "id": "2",
  "method": "tools/call",
  "params": {
    "name": "calculate-bmi",
    "arguments": {
      "weightKg": 180,
      "heightM": 1.8
    }
  }
}