Universal Modder troubleshooting — Setup, loaders & assets

The agent cannot find the skills

Check which installation route you used. For a clone, open the repository as the workspace so the agent can discover its instructions and skills. For a plugin, confirm the plugin is installed and start a new agent session.

The clone includes skills in skills/, .agents/skills/, and .claude/skills/ for the supported discovery paths. A skills-only install does not include every CLI and MCP setup step.

“um: command not found”

Check whether the CLI is installed in the same environment as your agent. A Windows PowerShell install and a WSL install have different executable paths.

uv tool install git+https://github.com/rehan-remade/universal-modder
um --help

If uv reports that its executable directory is missing from PATH, follow uv’s instructions and reopen your terminal. Ask the agent to diagnose its own environment before reinstalling repeatedly.

Asset generation fails

Check whether you chose the fal or local ComfyUI route. For fal, verify that the process running your agent received FAL_KEY, that the account can generate with the selected model, and that the error is not a rate or billing limit. Keep the key out of logs you share.

For local images, confirm that your ComfyUI server is running before inspecting the integration:

um comfy status

Use command --help output for model and workflow options. A retry will not solve a missing key, incompatible workflow, or unavailable model.

The mod builds, but the game will not load it

Compare the exact game version, mod loader version, and runtime against the field note. Mono and IL2CPP Unity builds need different routes; Minecraft loaders and versions are also not interchangeable.

Test the unmodified game with a separate save.
Test the loader alone.
Add your one minimal mod and capture its log.
Introduce additional mods only after that baseline works.

Ask the agent to inspect the first relevant error, not just the last line in a long crash log.

The game crashes or a save will not load

Stop making changes to the affected save. Restore the documented backup or work from a copy, then remove the latest change and reproduce the issue in a test environment. Record whether the crash happens on startup, world load, or a particular action.

Diagnose this failure from the game and loader logs. List the versions, the last change, and the first relevant error. Propose one reversible test. Do not edit or overwrite my existing saves.

Give the next person enough to reproduce it

A useful report includes your operating system, game and loader versions, installation route, the expected behavior, actual behavior, relevant logs with secrets removed, and the smallest steps that reproduce the problem.

Check the official issue tracker for existing reports. Include what you tried and clearly separate toolkit problems from a particular mod or loader issue.