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.
node
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.
workflow
jest --maxWorkers=50% --workerIdleMemoryLimit=512MB# raise heap if neededNODE_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.
Run jest --runInBand to surface the real stack.
Identify the test or native module that crashes.
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.
Frequently asked questions
What causes ""Worker terminated""?
Too many parallel workers, each holding heavy modules or leaking, exhaust runner RAM and the OS kills a worker.
How do I fix "Worker terminated"?
Lower maxWorkers and increase the per-process heap so workers do not exhaust memory.
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.
