openai/codex · error · anyhow::Error

handshake succeeded but server info was missing

Error message

handshake succeeded but server info was missing

What it means

Error "handshake succeeded but server info was missing" thrown in openai/codex.

Source

Thrown at codex-rs/rmcp-client/src/rmcp_client.rs:618

                    None => return Err(anyhow!("client already initializing")),
                },
                ClientState::Ready { .. } => return Err(anyhow!("client already initialized")),
                ClientState::Closed => return Err(anyhow!("MCP client is shut down")),
            }
        };

        let (service, oauth_persistor) = self
            .connect_pending_transport_with_initialize_retries(
                pending_transport,
                client_service.clone(),
                timeout,
            )
            .await?;

        let initialize_result_rmcp = service
            .peer()
            .peer_info()
            .ok_or_else(|| anyhow!("handshake succeeded but server info was missing"))?;
        let initialize_result = initialize_result_rmcp.as_ref().clone();

        {
            let mut initialize_context = self.initialize_context.lock().await;
            *initialize_context = Some(InitializeContext {
                timeout,
                client_service,
            });
        }

        {
            let mut guard = self.state.lock().await;
            if matches!(*guard, ClientState::Closed) {
                return Err(anyhow!("MCP client is shut down"));
            }
            *guard = ClientState::Ready {
                service,
                oauth: oauth_persistor.clone(),

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/rmcp-client/src/rmcp_client.rs:618 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/6cc86645ef12bc51. Report an issue: GitHub.