Anyone else hitting 424 / TaskGroup errors when creating a custom MCP connector?

API Bugs
1

Hi all,

I’m experimenting with MCP connectors in Developer Mode and ran into something odd.

When I try to add a custom MCP connector, the ChatGPT UI fails with a 424 error:

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

On my side:

  • My MCP server is public and healthy.

  • It responds correctly to initialize, tools/list (with both “search” and “fetch”), and tools/call.

  • Responses are valid JSON-RPC 2.0 and match the MCP docs.

  • Curl checks all return 200 OK.

  • Logs show no new requests at the moment the 424 appears, so it seems to fail in the validator before hitting the server.

Has anyone else seen this recently? Curious whether this is a known validator issue or if there are hidden handshake requirements not in the docs.

Thanks!