I have someone on my server who chose the Arachne class. Whenever they melee an enemy it crashes the server not sure if this is a bug from the poison bite ability or if its something on my end I can fix on the server.

Below crash error.
java.lang.NoSuchMethodError'int net.minecraft.class_2170.method_9249(net.minecraft.class_2168, java.lang.String)'

Any help would be greatly appreciated.

Same error when playing as Siren.

Same error when playing as Siren.

Weirdly enough more than half the classes crash when using this with Midieval MC Mod