windmill-labs/windmill · error

agent_config must be set in agent mode

Error message

agent_config must be set in agent mode

What it means

Construction guard for WorkerConn in main.rs: when the server runs in Mode::Agent, each worker's connection must carry an agent configuration. The error fires when mode is Agent but no agent_config was supplied (missing/empty AGENT env or config file), so the WorkerConn would be unusable.

Source

Thrown at backend/src/main.rs:1408

                        base_internal_url.clone(),
                    )?;
                    let mut workers = vec![];

                    for i in 0..num_workers {
                        let suffix = if i == 0 && first_suffix.is_some() {
                            first_suffix.as_ref().unwrap().clone()
                        } else {
                            resolve_worker_suffix(&hostname, i as usize + 1)?
                        };

                        let worker_conn = WorkerConn {
                            conn: if i == 0 || mode != Mode::Agent {
                                conn.clone()
                            } else {
                                Connection::Http(
                                    agent_config
                                        .as_ref()
                                        .expect("agent_config must be set in agent mode")
                                        .build_http_client(&suffix),
                                )
                            },
                            worker_name: checked_worker_name(
                                mode == Mode::Agent,
                                WORKER_GROUP.as_str(),
                                &suffix,
                            )?,
                        };
                        workers.push(worker_conn);
                    }

                    run_workers(
                        rx,
                        killpill_tx.clone(),
                        base_internal_url.clone(),
                        hostname.clone(),
                        &workers,

View on GitHub (pinned to e474e8803c)

Solutions

1. Set the agent configuration required by agent mode (agent config file / AGENT_* settings) before starting the server
2. Start the server without agent mode if agent behavior is not intended
3. Verify the agent worker config env vars are present in the deployment environment

When it happens

Trigger: Thrown at backend/src/main.rs:1408 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/af32d445ecb51092. Report an issue: GitHub.