How to Fix a Crash Caused by a Missing YUNG's API

Recognizing the Missing API Crash

If your game crashes on startup or when loading a world and the crash log mentions a YUNG's mod (Better Caves, Better Mineshafts, Better Portals, Better Strongholds, Better Dungeons, Bridges, Extras, Traveler's Titles, or Paxi), the most common cause is that YUNG's API is not installed. YUNG's API is a library mod — it does not add content on its own, but every YUNG's mod depends on it to run.

Fixing the Problem

1. Open your mods folder and check whether a YUNG's API jar is present alongside the mod that crashed.

2. If it is missing, add the YUNG's API file that matches your Minecraft version and mod loader (Fabric, Forge, or NeoForge).

3. If it is present but the crash persists, confirm the API version matches the mod loader and game version the other mods expect — a mismatched loader is a frequent culprit.

4. Remove any duplicate or outdated API jars so only one copy loads.

5. Relaunch the game. If the crash log still references YUNG's API, read the top of the log for the specific class or method it could not find, which usually points to a version mismatch rather than a missing file.

Once the API loads correctly, the dependent mods will register their structures and features normally.