Mixin failures

SpongeForge Startup Crash: org.spongepowered.mod.mixin.handler.MixinErrorHandler

What the log looks like

Instancing error handler class org\.spongepowered\.mod\.mixin\.handler\.MixinErrorHandler
org\.spongepowered\.mod\.mixin\.handler\.MixinErrorHandler

How to fix it

  1. Open logs/fml-server-latest.log or logs/latest.log and read the /* ... */ Sponge diagnostic box right below the MixinErrorHandler line to confirm which class or coremod conflicted.
  2. Rename your SpongeForge jar in the mods folder to start with _aa_ (for example, _aa_spongeforge-1.10.2-2281-5.2.0.jar) or install SpongeBootstrap so Sponge loads before alphabetical coremods like Applied Energistics 2.
  3. Check that your Forge server version matches the Forge build number in the SpongeForge jar name (for example, spongeforge-1.10.2-2281 requires Forge build 2281, not an older build like 2099).
  4. If you are running early alpha builds of mods such as Applied Energistics 2 rv4-alpha on 1.10.2, update both SpongeForge and the offending mod to their latest stable releases for your Minecraft version.
LoadersForge, Server
SeverityStops the game
CategoryMixin failures

Check your own log

Related errors

Mixin failuresCritical injection failure — a mixin could not find its targetTwo mods are usually fighting over the same game methodMixin failuresInvalidMixinException: Mod Mixin Failed to ApplyOpen your latest.log or crash report and look for 'Mixin apply for mod' or the 'Config :' line inside the 'InvMixin failuresInvalidMixinException: Unexpecteded ClassMetadataNotFoundExceptionFind the line saying 'Mixin apply for mod <modname> failed' or 'from mod <modname>' right above the error in yMixin failuresMixin Transformation of net.minecraft.client.main.Main FailedOpen latest.log or the launcher crash output and look at the Caused by lines below Mixin transformation of netMixin failuresMixin apply failed — one mod could not patch the gameThe line names the mixin config, and its prefix is the mod id that brokeMixin failuresMixinExtras is missing or too oldUpdate the mod that needs it — modern mods bundle MixinExtras themselves