openai/codex · error · anyhow::Error

MCP client is shut down

Error message

MCP client is shut down

What it means

Error "MCP client is shut down" thrown in openai/codex.

Source

Thrown at codex-rs/rmcp-client/src/rmcp_client.rs:603

        &self,
        params: InitializeRequestParams,
        timeout: Option<Duration>,
        send_elicitation: SendElicitation,
    ) -> Result<ServerPeerInfo> {
        let client_service = ElicitationClientService::new(
            params.clone(),
            send_elicitation,
            self.elicitation_pause_state.clone(),
        );
        let pending_transport = {
            let mut guard = self.state.lock().await;
            match &mut *guard {
                ClientState::Connecting { transport } => match transport.take() {
                    Some(transport) => transport,
                    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();

        {

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/rmcp-client/src/rmcp_client.rs:603 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/9a8ac7e0bc8cadb6. Report an issue: GitHub.