Corrupted files

NoClassDefFoundError on a mod class — that mod did not load

What it looks like in the log

noclassdeffounderror: … /…
classnotfoundexception: … .…

How to fix it

  1. The first word of the class path is the mod id — that is the mod that failed to load
  2. Open the log higher up and look for that mod id in the FML mod list: it is probably listed as errored, or missing entirely
  3. Re-download that jar for your exact Minecraft and Forge version; a half-downloaded jar gives exactly this
  4. If two copies of the mod are in the folder, delete the older one
LoadersForge
SeverityStops the game
CategoryCorrupted files

Check your own log

Related errors

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