The problem
Fix exit code 255 in modded Minecraft. Common causes are mods that cannot load, an incompatible Java version and broken JVM arguments.
Possible causes
- A mod failed during loading and the loader closed the game.
- The Java version is too new or too old for the Minecraft version.
- JVM arguments the Java runtime rejects.
- A corrupted loader or library download.
How to identify the cause
- Read the end of
logs/latest.logand the newest crash report. Look forModLoadingException,Caused byor a "missing dependency" message. - Compare the Java version shown at the top of the log with what your Minecraft version needs.
Step-by-step fix
- Fix any mod named in the crash report by updating it or removing it.
- Install any dependency the log reports as missing.
- Use the Java version your Minecraft version expects. See Java versions for Minecraft.
- Remove custom JVM arguments.
- Reinstall the loader for the instance.
If that did not work
- Split your mods in half and test each half to find the mod that causes the crash.
Affected versions
All Minecraft versions, Java Edition. Most common with Forge and NeoForge instances.
Frequently asked questions
Does exit code 255 mean my world is broken?
No. It happens before or while the game loads. Your saves are not touched, but back them up before big changes anyway.