Single-process n8n does everything in one Node.js process: editor, webhooks, executions. It works until a heavy Code node holds the event loop hostage and the whole instance stutters. Queue mode splits the world — main (UI, API), webhook processors (receive and enqueue), workers (consume and execute) — coordinated through Redis-backed queues. Add workers, multiply throughput. The architecture is correct by design; it just introduces its own quiet failure surface exactly where the single-process version was loud.

Trap 1 — WEBHOOK_URL and the split listener

The editor shows you a workflow's webhook, but traffic lands on the webhook processors. A mispointed WEBHOOK_URL gives callers a URL reaching the main process — or nothing. Deactivate your intuition: verify by curling the production URL from outside after every infra change.

Trap 2 — Registration drift after restarts

A webhook registration is owned by the specific processor process that created it.…