Error: Process completed with exit code 137.

Why this happens

• Browsers, the app under test, and the test runner together use more memory than the runner has
• A Docker container has a memory limit lower than what the job needs
• Too many parallel test workers or browser instances are running at once
• The job hit its timeout and the platform force-killed it

How to fix it

1. Cut parallelism first (fewer workers, one browser project per job) and see whether the kill goes away
2. Move to a larger runner, or raise the container's memory limit
3. Shard the suite across several jobs instead of running everything on one machine
4. Check the step's duration too. If it stopped right at the timeout, this is a hang, not a memory problem

Example

              strategy:
  matrix:
    shard: [1, 2, 3, 4]
steps:
  - run: npx playwright test --shard=${{ matrix.shard }}/4 --workers=2