Nuxt "JavaScript heap out of memory" during build in CI

By Daniel Zoghalchali·Latchkey

Node's V8 heap has a default ceiling. A large Nuxt build (many pages, big dependencies, source maps) can exceed it on a CI runner with limited memory, and the process aborts with a heap allocation failure.

What this error means

nuxt build fails with "FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory" and a V8 stack trace. It builds locally where more memory is available.

nuxt

<--- Last few GCs --->
FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory
 1: 0xb... node::Abort()
 2: 0xc... v8::internal::Heap::FatalProcessOutOfMemory(...)

Common causes

The build exceeds the default V8 heap

Bundling a large app with source maps and many modules needs more memory than Node allocates by default on the runner.

A memory-constrained runner

A smaller CI runner has less RAM than a developer machine, so the same build that passes locally hits the limit.

How to fix it

Raise the Node heap limit

Increase --max-old-space-size so V8 can use more of the runner's memory.

.github/workflows/ci.yml

env:
  NODE_OPTIONS: --max-old-space-size=4096

Reduce build memory pressure

Disable client source maps in production if not needed.
Use a runner with more memory for the build job.
Split or trim heavy dependencies pulled into the bundle.

nuxt.config.ts

export default defineNuxtConfig({
  sourcemap: { client: false }
});

How to prevent it

Set NODE_OPTIONS=--max-old-space-size to match the runner memory.
Disable unneeded source maps in production builds.
Size the build runner for the app, not the smallest available.

Frequently asked questions

What causes ""JavaScript heap out of memory""?

Bundling a large app with source maps and many modules needs more memory than Node allocates by default on the runner.

How do I fix "JavaScript heap out of memory"?

Increase --max-old-space-size so V8 can use more of the runner's memory.