Resolve Startup Crashes after Installing Cauldron or MCPC-Plus

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This article is archived. The information provided here does not apply to present day servers and links on this page may be dead. The information is being provided for posterity.

After installing Cauldron to a modpack that includes MobiusCore and Opis, like Feed the Beast Monster, your Minecraft server may no longer start. The following error appears:

\[SEVERE\] java.lang.IncompatibleClassChangeError: Class mcp.mobius.mobiuscore.profiler.DummyProfiler does not implement the requested interface mcp.mobius.mobiuscore.profiler.IProfilerHandler
\[SEVERE\] 	at cpw.mods.fml.common.FMLCommonHandler.tickStart(FMLCommonHandler.java:127)
\[SEVERE\] 	at cpw.mods.fml.common.FMLCommonHandler.onWorldLoadTick(FMLCommonHandler.java:318)
\[SEVERE\] 	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:643)
\[SEVERE\] 	at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)
\[SEVERE\] Encountered an unexpected exception IncompatibleClassChangeError
java.lang.IncompatibleClassChangeError: Class mcp.mobius.mobiuscore.profiler.DummyProfiler does not implement the requested interface mcp.mobius.mobiuscore.profiler.IProfilerHandler
	at cpw.mods.fml.common.FMLCommonHandler.tickStart(FMLCommonHandler.java:127)
	at cpw.mods.fml.common.FMLCommonHandler.onWorldLoadTick(FMLCommonHandler.java:318)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:643)
	at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)

You may also see:

\[SEVERE\] java.lang.NoClassDefFoundError: net/minecraftforge/event/ASMEventHandler
\[SEVERE\] 	at net.minecraftforge.event.EventBus.register(EventBus.java:77)
\[SEVERE\] 	at net.minecraftforge.event.EventBus.register(EventBus.java:58)
\[SEVERE\] 	at binnie.core.BinnieCoreMod.(BinnieCoreMod.java:36)
\[SEVERE\] 	at binnie.core.BinnieCore.(BinnieCore.java:76)

Cauldron has made some changes that caused MobiusCore to become incompatbile. To resolve the issue, remove it and MobiusCore from your server:

1. Login to your server FTP.
2. Open the folder of the game that you installed Cauldron to.
3. Open mods.
4. Delete MobiusCore_[version].jar and Opis_[version].jar.
5. Start your server.

If you want to use Opis, we suggest you to download and install the latest versions intended for the version of Minecraft your server is based on.