MCP connector creation fails with 424 / TaskGroup error (endpoint never contacted)

ChatGPT
,
1

I’m running into an issue when trying to register a custom MCP connector.

When creating the connector in ChatGPT (Developer Mode → Connectors → Add New Connector), the request to chat GPT fails with:

{“detail”:“unhandled errors in a TaskGroup (1 sub-exception)”}

My setup:

  • Developer Mode is enabled.

  • MCP server is publicly reachable and responds with valid JSON-RPC 2.0.

  • Verified with curl, which returns a valid initialize response with protocolVersion, capabilities, and serverInfo.

  • tools/list returns exactly two tools: search and fetch.

  • tools/call works for both.

  • Logs confirm my server is never re-contacted when the 424 happens—the error occurs on the ChatGPT side before any further call.

Steps to reproduce:

  1. Enable Developer Mode.

  2. Try to add the connector with a valid MCP server URL.

  3. Observe 424 from chatgpt/mcp with the TaskGroup error.

Expected:

The validator should attempt to handshake with the MCP server and surface any protocol/schema errors if present.

Actual:

The connector fails creation immediately with a 424 / TaskGroup error, even though the MCP server passes all spec checks via curl.

Notes:

  • All required fields and tools are present.

  • No extra fields are returned.

  • This looks like a validator-side bug or regression, consistent with similar developer reports.

Has anyone else run into this? Is this a known MCP validator issue?

1 Like
4

This topic was automatically closed after 24 hours. New replies are no longer allowed.