openai/codex · error · StartupOutcomeError

MCP client startup timed out after {startup_timeout:?}

Error message

MCP client startup timed out after {startup_timeout:?}

What it means

Error "MCP client startup timed out after {startup_timeout:?}" thrown in openai/codex.

Source

Thrown at codex-rs/codex-mcp/src/rmcp_client.rs:355

                let client = match tokio::time::timeout(
                    startup_timeout,
                    make_rmcp_client(
                        &server_name,
                        server.clone(),
                        store_mode,
                        keyring_backend_kind,
                        runtime_context,
                        resolved_environment,
                        runtime_auth_provider,
                        protocol_mode,
                    ),
                )
                .await
                {
                    Ok(result) => Arc::new(result?),
                    Err(_) => {
                        return Err(StartupOutcomeError::from(anyhow!(
                            "MCP client startup timed out after {startup_timeout:?}"
                        )));
                    }
                };
                start_server_task(
                    server_name,
                    client,
                    StartServerTaskParams {
                        is_codex_apps_mcp_server,
                        startup_timeout: Some(startup_timeout),
                        tx_event,
                        elicitation_requests,
                        codex_apps_tools_cache_context,
                        tool_catalog_cache_context,
                        tool_catalog_fetch_ticket,
                        client_elicitation_capability,
                        client_mcp_extensions,
                        catalog_item_limit,

View on GitHub (pinned to 339751715c)

Solutions

1. Increase `startup_timeout` for the MCP server or fix the server to start faster; check the server logs for the stall.

When it happens

Trigger: Thrown at codex-rs/codex-mcp/src/rmcp_client.rs:355 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/591bcad9830a682d. Report an issue: GitHub.