스크립트로 서버 만들다가  커맨드 블럭을 사용하기위해  sever.properties에서 커맨드 블럭 사용 true 바꾸고 서버를 여니까

Description: Exception in server tick loop

java.lang.NoClassDefFoundError: net/minecraft/entity/Entity$2

    at net.minecraft.entity.Entity.func_85029_a(Entity.java:3081)

    at net.minecraft.entity.Entity.func_70020_e(Entity.java:2160)

    at net.minecraft.entity.EntityList.func_75615_a(EntityList.java:226)

    at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_186053_a(AnvilChunkLoader.java:607)

    at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_186050_a(AnvilChunkLoader.java:534)

    at net.minecraft.world.chunk.storage.AnvilChunkLoader.loadEntities(AnvilChunkLoader.java:488)

    at net.minecraftforge.common.chunkio.ChunkIOProvider.syncCallback(ChunkIOProvider.java:101)

    at net.minecraftforge.common.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:151)

    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:936)

    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:475)

    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:834)

    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:693)

    at java.lang.Thread.run(Unknown Source)

이렇게 뜨네요..