Jest "Worker terminated" - Worker Crashed in CI

A Jest worker process exited abnormally. The most common cause is memory exhaustion under high worker concurrency, though a native crash or an unhandled exception in a worker can also terminate it.

What this error means

A test run fails with "Jest worker encountered N child process exceptions" or a terminated worker. It can be intermittent and worsens as worker count or memory pressure rises.

Jest worker encountered 4 child process exceptions, exceeding retry
limit
    at ChildProcessWorker._onExit (.../jest-worker/build/workers/ChildProcessWorker.js:521:23)

Common causes

Workers ran out of memory

Too many parallel workers, each holding heavy modules or leaking, exhaust runner RAM and the OS kills a worker.

A native crash or unhandled error in a worker

A segfaulting native addon or an uncaught exception inside a worker terminates the process abnormally.

How to fix it

Reduce worker concurrency and raise heap

Lower maxWorkers and increase the per-process heap so workers do not exhaust memory.

jest --maxWorkers=50% --workerIdleMemoryLimit=512MB
# raise heap if needed
NODE_OPTIONS=--max-old-space-size=4096 jest

Isolate the crashing test

Run with --runInBand to find the test that crashes the worker, then fix the leak or native issue.

1. Run jest --runInBand to surface the real stack.
2. Identify the test or native module that crashes.
3. Fix the leak / native incompatibility or quarantine the test.

How to prevent it

• Cap test worker concurrency relative to runner RAM.
• Use a per-worker idle memory limit to recycle leaky workers.
• Quarantine known native-crashing tests until fixed.

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