Mixin failures

java.lang.VerifyError: Bad return type

What it looks like in the log

java.lang.VerifyError: Bad return type

How to fix it

  1. Look at the `Location:` line and stack trace directly below `java.lang.VerifyError: Bad return type`; if it mentions `Config.` or `detectOptifine`, remove OptiFine from your `mods` folder or install the exact build made for your Minecraft and Forge version.
  2. Inspect your `mods` folder (including versioned subfolders inside `mods`) and remove any JAR built for a different Minecraft version, especially coremods and rendering mods.
  3. Check the `WARNING: coremods are present:` list at the top of the crash report or the `locals:` list under `Current Frame:` to identify coremods or Mixins touching the broken class.
  4. Update your mod loader and the mods modifying the class shown under `Location:`, or test without recently added performance/tweaker mods to isolate conflicting bytecode patches.
LoadersForge, Neoforge, Fabric, Quilt
SeverityStops the game
CategoryMixin failures

Check your own log

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