Node crash

Updated 11 October 2026

Short answer

When a Node.js app hits an error nothing catches, Node prints the stack trace and exits, so your site goes down. The stack trace is the answer: it names the error and the line. Find it in your process manager's or platform's logs. If there's no stack trace at all, the process was probably killed from outside, usually by the system running out of memory. Either way, run Node under a process manager that restarts it, so one crash isn't an outage.

What's the problem

Your Node.js app stops, the site gives 502 errors or doesn't respond, and the logs end with a stack trace, or just stop.

Why it happens

  • An uncaught exception: an error thrown outside any try/catch.
  • An unhandled promise rejection: an async call that failed without a catch.
  • Out of memory: a leak or a large job, ending in the system killing the process.
  • A missing environment variable or dependency at startup.
  • A port already in use when restarting.

How to fix it

  1. Find the last stack trace in your logs (PM2, systemd's journalctl, Docker, or your platform).
  2. Fix the error at that line, and handle errors in async code.
  3. If there's no trace, check for out-of-memory kills. See out of memory.
  4. Run under a process manager (PM2, systemd, Docker restart policy) so it restarts automatically.
  5. Check startup configuration if it crashes immediately.

What Preventionlabs checks

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Sources

  1. Node.js: Processofficial docsBy default, Node.js handles such exceptions by printing the stack trace to stderr and exiting with code 1, overriding any previously set process.exitCode .
  2. The Linux Kernel documentation: Documentation for /proc/sys/vm/official docsIf this is set to zero, the OOM killer will scan through the entire tasklist and select a task based on heuristics to kill. This normally selects a rogue memory-hogging task that frees up a large amount of memory when killed.

Related

Express error Express handles errors through middleware with four arguments (err, req, res, next). Make sure async errors reach it, and log the error before responding. Out of memory: process killed The server ran out of memory and Linux killed a process to survive, often your app or database. Confirm it in the system log, then find what used the memory. Server crash Find out what crashed (the whole machine, or just your app or database), then read the logs from just before. Most crashes are memory, disk, or a code change. 502 Bad Gateway The server in front of your app got a bad answer, or none, from your app. Usually the app has crashed, isn't running, or is listening on the wrong port.

Preventionlabs is independent and not affiliated with Node.js. Product names are used only to describe the problem.

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