How to Troubleshoot YUNG's API Conflicts and World Gen Errors

Common Symptoms

Because YUNG's API handles world generation helpers and structure placement for its dependent mods, problems often show up as missing structures, broken jigsaw pieces, or errors during chunk generation rather than a clean crash. Symptoms include structures failing to appear, log spam about jigsaw or structure checks, or worlds that generate partially.

Step-by-Step Troubleshooting

1. Confirm the API version matches your game version and loader. Most world-gen errors trace back to a version mismatch.

2. Check for duplicate API jars — two copies can cause registration conflicts.

3. Look at the log for lines mentioning jigsaw managers or structure existence checks; these come from the API and usually indicate a dependent mod is out of sync with the API build.

4. Update all YUNG's mods together so they share a compatible API version, since mixing old and new builds causes structure errors.

5. If a specific structure is missing, verify the mod that adds it is installed and enabled — the API only provides the tools, not the structure itself.

After Fixing

Generate a fresh world or explore new chunks to test, since already-generated terrain will not retroactively gain structures. Existing chunks keep whatever generated before the fix.