GitHub Actions: Error: Process completed with exit code 1

Error: Process completed with exit code 1. is not the error itself. The runner prints it when the shell running a run: step exits with status 1. On Linux and macOS the default shell is bash -e, so the step stops at the first command that fails, and that command's own output, just above, says what went wrong.

Find the real cause

1. Open the failed step and scroll up from the message to the first error, FAIL or stack trace.
2. Look at which command ran last: with bash -e, nothing after it was executed.
3. If the log is not enough, re-run the job with Re-run jobs → Enable debug logging.

Common case: grep with no match

grep exits 1 when it finds nothing, and bash -e turns that into a failed step:

- run: grep -q "TODO" src/*.js && echo "found TODOs"           # fails the step when there are none
- run: grep -q "TODO" src/*.js && echo "found TODOs" || true   # never fails

Allow a step to fail

- name: Optional lint
  run: npm run lint
  continue-on-error: true

The job continues and stays green; the step is shown as failed but does not fail the job. Use if: failure() on a later step to react only when something earlier failed.