Worker-Specific Errors

These errors are specific to running MOSAIC workers (training backends). For shared errors that apply to all platforms, see the parent Common Errors page.

Per-Worker Error Guides

Shared Worker Errors

The errors below can occur with any worker that uses the affected tool or library.

jq: command not found in Curriculum Training Scripts

Error:

/path/to/mosaic/scripts/curriculum_babyai_goto.sh: line 78: jq: command not found

Cause: The jq command-line JSON processor is not installed on the system. CleanRL curriculum training scripts (e.g. curriculum_babyai_goto.sh) use jq to build the curriculum schedule JSON from the base MOSAIC config file. This is a system dependency, not a Python package, so pip install will not provide it.

Context: This error occurs when you launch a custom script through the CleanRL training form (cleanrl_script_form.py). The script reads MOSAIC_CONFIG_FILE, then pipes it through jq to inject curriculum stages, algorithm parameters, and output directories into the JSON config.

Fix:

# Ubuntu / Debian / WSL
sudo apt-get update && sudo apt-get install -y jq

# Verify installation
jq --version

After installing jq, re-run the training script from the GUI. No restart of the MOSAIC application is required – the next subprocess launch will pick up the newly installed binary.

Note

If you are provisioning a fresh environment (CI, Docker, new WSL distro), add jq to your system-level dependency list alongside other non-Python prerequisites such as git, curl, and build-essential.