# Node.js ERR_WORKER_OUT_OF_MEMORY - Fix Worker Terminated by Memory Limit

> Fix Node.js ERR_WORKER_OUT_OF_MEMORY "Worker terminated due to reaching memory limit" in CI - a worker’s resourceLimits ceiling, not the parent heap, was exceeded.

Source: https://latchkey.dev/learn/node-js/node-err-worker-out-of-memory  
Updated: 2026-06-25

ERR_WORKER_OUT_OF_MEMORY is the specific error a parent thread receives when a Worker exceeds the heap ceiling set by its own `resourceLimits` (or the implicit default). It is distinct from a plain heap crash because the limit it hit was configured on the worker, not via NODE_OPTIONS.

## Diagnose it: what is different about the runner?

A build that passes locally and fails on a runner differs in a small number of predictable ways. Check those before changing build configuration, because the build config is usually not the thing that changed.

```.github/workflows/ci.yml
- run: |
    node --version && npm --version
    echo "NODE_ENV=$NODE_ENV  CI=$CI"
    nproc && free -h && df -h /
    ls -la node_modules/.bin | head
```

> `CI=true` is set on every runner and changes behaviour in several toolchains, most commonly by promoting warnings to errors. Reproduce locally with `CI=true npm run build` before assuming the runner is broken.

## The three that account for most of them

- **Case sensitivity.** Linux runners are case sensitive, macOS is not. An import with the wrong case resolves locally and fails in CI.
- **Out of memory.** Exit code 137 is a SIGKILL from the kernel, not a build error. Raise `--max-old-space-size` or use a larger runner.
- **devDependencies pruned.** `NODE_ENV=production` makes `npm ci` skip devDependencies, so the build tool itself goes missing. Set it after install, not before.

## FAQ

### What causes Node.js ERR_WORKER_OUT_OF_MEMORY?

There are 2 common causes: resourcelimits set too low for the worker and the implicit per-worker default is too small. A Worker created with a small maxOldGenerationSizeMb hits that ceiling and is terminated, surfacing this code to the parent - even though the parent had plenty of headroom.

### How do I fix Node.js ERR_WORKER_OUT_OF_MEMORY?

There are 2 fixes depending on which cause you have: raise the worker’s resourcelimits and shrink the worker’s footprint. Work through them in order, since the first is the most common.

### What does Node.js ERR_WORKER_OUT_OF_MEMORY actually mean?

The main thread catches an error event with code ERR_WORKER_OUT_OF_MEMORY and a message that the worker was terminated for reaching its memory limit.

### How do I stop Node.js ERR_WORKER_OUT_OF_MEMORY happening again?

Set worker resourceLimits deliberately, sized to the runner. The prevention section lists 3 changes that keep it from recurring.

### Can Latchkey fix this automatically?

Yes. Latchkey runs your GitHub Actions on managed runners that detect this failure, apply the fix, and retry the job automatically - self-healing is on by default.

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Latchkey runs CI/CD that repairs its own failures. Agent entry points: https://latchkey.dev/agent.txt, https://latchkey.dev/openapi.json, https://latchkey.dev/llms.txt