AgentFixboard
Fixed (verified)Last checked Hermes Agent#setup#error-messages

Scheduled cron jobs fail with "No module named 'ruamel'" before they start

Every scheduled cron job fails before it runs. The scheduler reports Restart-safe cron worker dispatch failed: cron external worker exited before ownership acknowledgement (exit 1) and worker stderr ends in ModuleNotFoundError: No module named 'ruamel'.

From GitHub

NousResearch/hermes-agent

IssuePull request

Difficulty
Easy
Time
~5 min
Steps
2
Fixed in
v0.21.6
Last checked

Verified fix: PR #126344 merged on . Fixed in v0.21.6 (first published release whose tag contains the merge commit). Last checked .

Symptom

Every scheduled cron job fails before it runs. The scheduler reports Restart-safe cron worker dispatch failed: cron external worker exited before ownership acknowledgement (exit 1) and worker stderr ends in ModuleNotFoundError: No module named 'ruamel'.

Evidence what you'll see

  • The traceback in the report is File ".../hermes-agent/hermes_yaml.py", line 10, in <module> then from ruamel.yaml import YAML then ModuleNotFoundError: No module named 'ruamel'.
  • The run is stored FAILED (last_status: failed) and the job never executes.
  • The issue's direct probe is PYTHONPATH="$HERMES_HOME/hermes-agent" "$STORE" -m cron.scheduler --help, which raises that ModuleNotFoundError.

Why it happens

The restart-safe worker is spawned as sys.executable -m cron.scheduler with a sanitized environment. On a self-managed install that interpreter is the store Python, which owns no third-party packages, and the sanitizer also drops the committed generation's site-packages. Importing cron.jobs then loads hermes_yaml → ruamel before the worker can write its ownership acknowledgement. Pull request 126344 pins the committed generation on the worker PYTHONPATH and runs pm.environments.activate_dependencies at the top of cron/__init__.py so that boot happens before cron.jobs.

Affected versions

Linux x86_64, self-managed shell-installer install (not wheel, pipx, or Nix). Hermes main at 0b724b178. Store Python 3.14.7. Dependency generation under $HERMES_HOME/installs/<id>/environments/<hash>/venv.

Fix steps

0 of 2 done

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How to check it worked

  • A restart-safe cron job on a self-managed install publishes its ownership acknowledgement and finishes, instead of exiting 1 with ModuleNotFoundError: No module named 'ruamel'.

If it still fails

  • Tag v2026.9.24 does not contain pull request 126344. Stay on v0.21.6 or later.
  • Pull request 126344 says a damaged committed generation now exits before the acknowledgement, and the gateway reports that dispatch failure with the worker stderr, instead of running on an unleased path.

Sources and credit

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