The most common MCP connection errors — -32000, -32001, -32601 — and how to fix each one. Paste your server URL below and gate will connect, run the handshake, and tell you exactly which error it hits (and grade its security while it’s there).
-32000 — Connection closedCause: The server accepted the TCP/HTTP connection but closed it during the MCP handshake (initialize / tools/list).
Fix: Most often the URL isn't a Streamable-HTTP MCP endpoint — it may be an SSE-only or stdio server, or the MCP path is wrong. Use the server's remote /mcp URL, and confirm it speaks the Streamable-HTTP transport.
-32001 — Request timed outCause: The server didn't respond to the request within the client's timeout.
Fix: It may be cold-starting, slow, or blocking your region. Retry, raise the client timeout, or check the server is up and reachable from the internet.
-32601 — Method not foundCause: The endpoint responded, but doesn't implement the MCP JSON-RPC methods (e.g. initialize, tools/list).
Fix: This usually means the URL points at a normal HTTP API, not an MCP server. Point the client at the actual MCP endpoint.
-32700 / -32600 — Parse error / Invalid requestCause: The endpoint replied, but not with valid JSON-RPC — the client couldn't parse it.
Fix: The URL is probably not an MCP server, or a proxy is rewriting the response. Verify the endpoint directly.
Servers that require OAuth can’t be reached without credentials, so a token error is expected there — connect those inside gate.