Unhandled 'error' event 🟩 Node.js

Error: Unhandled 'error' event (events.js / node:events)

An EventEmitter (stream, socket, child process, server) emitted 'error' and nothing listened for it, so Node crashed.

Seen on: Node.js

Meaning

EventEmitters throw if an 'error' event has no listener. The underlying cause is printed below (ECONNRESET, ENOENT, EADDRINUSE…).

Common causes

  • No error handler on a stream/socket/child process
  • Server ‘error’ (port in use) not handled
  • Library emitting errors on idle connections (Redis, DB clients)

⚡ Quick fix

  1. Attach .on('error', handler) to emitters
  2. Read the nested cause in the stack trace
  3. Configure reconnect logic for clients

Detailed fix by platform

Node.js

  1. child.on('error', err => console.error('spawn failed', err));

How to diagnose

  1. Emitter — Which object emitted?
  2. Cause — What error is nested?

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