이렇게 뜨면서 버킷에는
  at net.minecraft.server.management.UserListOps.func_152681_a(UserListOps.java:46) ~[pm.class:?]
        at net.minecraft.server.management.UserListOps.func_152681_a(UserListOps.java:7) ~[pm.class:?]
        at net.minecraft.server.management.UserList.func_152692_d(UserList.java:128) ~[pp.class:?]
        at net.minecraft.server.management.PlayerList.func_152596_g(PlayerList.java:1493) ~[pl.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer.isOp(CraftPlayer.java:145) ~[CraftPlayer.class:?]
        at org.bukkit.permissions.PermissibleBase.isOp(PermissibleBase.java:36) ~[PermissibleBase.class:?]
        at org.bukkit.permissions.PermissibleBase.recalculatePermissions(PermissibleBase.java:150) ~[PermissibleBase.class:?]
        at org.bukkit.permissions.PermissibleBase.<init>(PermissibleBase.java:29) ~[PermissibleBase.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftHumanEntity.<init>(CraftHumanEntity.java:66) ~[CraftHumanEntity.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer.<init>(CraftPlayer.java:134) ~[CraftPlayer.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftEntity.getEntity(CraftEntity.java:128) ~[CraftEntity.class:?]
        at net.minecraft.entity.Entity.getBukkitEntity(Entity.java:123) ~[vg.class:?]
        at net.minecraft.entity.player.EntityPlayer.getBukkitEntity(EntityPlayer.java:2941) ~[aed.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.getBukkitEntity(EntityPlayerMP.java:1890) ~[oq.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.getBukkitEntity(EntityPlayerMP.java:136) ~[oq.class:?]
        at net.minecraft.entity.EntityLivingBase.func_110143_aJ(EntityLivingBase.java:936) ~[vp.class:?]
        at net.minecraft.entity.EntityLivingBase.func_70089_S(EntityLivingBase.java:1446) ~[vp.class:?]
        at slimeknights.toolleveling.EntityXpHandler.onCapabilityAttach(EntityXpHandler.java:21) ~[EntityXpHandler.class:?]
        at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_236_EntityXpHandler_onCapabilityAttach_AttachCapabilitiesEvent.invoke(.dynamic) ~[?:?]
        at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
        at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182) [EventBus.class:?]
        at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:658) [ForgeEventFactory.class:?]
        at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:628) [ForgeEventFactory.class:?]
        at net.minecraft.entity.Entity.<init>(Entity.java:268) [vg.class:?]
        at net.minecraft.entity.EntityLivingBase.<init>(EntityLivingBase.java:193) [vp.class:?]
        at net.minecraft.entity.player.EntityPlayer.<init>(EntityPlayer.java:168) [aed.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.<init>(EntityPlayerMP.java:188) [oq.class:?]
        at net.minecraft.server.management.PlayerList.allowUserToConnect(PlayerList.java:631) [pl.class:?]
        at net.minecraft.server.network.NetHandlerLoginServer.func_147326_c(NetHandlerLoginServer.java:131) [pc.class:?]
        at net.minecraft.server.network.NetHandlerLoginServer.func_73660_a(NetHandlerLoginServer.java:70) [pc.class:?]
        at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:285) [gw.class:?]
        at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:180) [oz.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:1013) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:454) [nz.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:855) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:706) [MinecraftServer.class:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_191]
[11:15:55] [Server thread/ERROR] [FML]: Index: 3 Listeners:
[11:15:55] [Server thread/ERROR] [FML]: 0: NORMAL
[11:15:55] [Server thread/ERROR] [FML]: 1: ASM: class gr8pefish.ironbackpacks.core.EventHandler attachPlayerCaps(Lnet/minecraftforge/event/AttachCapabilitiesEvent;)V
[11:15:55] [Server thread/ERROR] [FML]: 2: ASM: slimeknights.tconstruct.gadgets.item.ItemPiggybackPack@3731b39e attachCapability(Lnet/minecraftforge/event/AttachCapabilitiesEvent;)V
[11:15:55] [Server thread/ERROR] [FML]: 3: ASM: slimeknights.toolleveling.EntityXpHandler@4e1e5596 onCapabilityAttach(Lnet/minecraftforge/event/AttachCapabilitiesEvent;)V
[11:15:55] [Server thread/WARN] [net.minecraft.network.NetworkSystem]: Failed to handle packet for /192.168.50.1:57147
java.lang.NullPointerException: null
        at net.minecraft.server.management.UserListOps.func_152681_a(UserListOps.java:46) ~[pm.class:?]
        at net.minecraft.server.management.UserListOps.func_152681_a(UserListOps.java:7) ~[pm.class:?]
        at net.minecraft.server.management.UserList.func_152692_d(UserList.java:128) ~[pp.class:?]
        at net.minecraft.server.management.PlayerList.func_152596_g(PlayerList.java:1493) ~[pl.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer.isOp(CraftPlayer.java:145) ~[CraftPlayer.class:?]
        at org.bukkit.permissions.PermissibleBase.isOp(PermissibleBase.java:36) ~[PermissibleBase.class:?]
        at org.bukkit.permissions.PermissibleBase.recalculatePermissions(PermissibleBase.java:150) ~[PermissibleBase.class:?]
        at org.bukkit.permissions.PermissibleBase.<init>(PermissibleBase.java:29) ~[PermissibleBase.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftHumanEntity.<init>(CraftHumanEntity.java:66) ~[CraftHumanEntity.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer.<init>(CraftPlayer.java:134) ~[CraftPlayer.class:?]
        at org.bukkit.craftbukkit.v1_12_R1.entity.CraftEntity.getEntity(CraftEntity.java:128) ~[CraftEntity.class:?]
        at net.minecraft.entity.Entity.getBukkitEntity(Entity.java:123) ~[vg.class:?]
        at net.minecraft.entity.player.EntityPlayer.getBukkitEntity(EntityPlayer.java:2941) ~[aed.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.getBukkitEntity(EntityPlayerMP.java:1890) ~[oq.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.getBukkitEntity(EntityPlayerMP.java:136) ~[oq.class:?]
        at net.minecraft.entity.EntityLivingBase.func_110143_aJ(EntityLivingBase.java:936) ~[vp.class:?]
        at net.minecraft.entity.EntityLivingBase.func_70089_S(EntityLivingBase.java:1446) ~[vp.class:?]
        at slimeknights.toolleveling.EntityXpHandler.onCapabilityAttach(EntityXpHandler.java:21) ~[EntityXpHandler.class:?]
        at net.minecraftforge.fml.common.eventhandler.ASMEventHa

ndler_236_EntityXpHandler_onCapabilityAttach_AttachCapabilitiesEvent.invoke(.dynamic) ~[?:?]
        at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
        at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182) ~[EventBus.class:?]
        at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:658) ~[ForgeEventFactory.class:?]
        at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:628) ~[ForgeEventFactory.class:?]
        at net.minecraft.entity.Entity.<init>(Entity.java:268) ~[vg.class:?]
        at net.minecraft.entity.EntityLivingBase.<init>(EntityLivingBase.java:193) ~[vp.class:?]
        at net.minecraft.entity.player.EntityPlayer.<init>(EntityPlayer.java:168) ~[aed.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.<init>(EntityPlayerMP.java:188) ~[oq.class:?]
        at net.minecraft.server.management.PlayerList.allowUserToConnect(PlayerList.java:631) ~[pl.class:?]
        at net.minecraft.server.network.NetHandlerLoginServer.func_147326_c(NetHandlerLoginServer.java:131) ~[pc.class:?]
        at net.minecraft.server.network.NetHandlerLoginServer.func_73660_a(NetHandlerLoginServer.java:70) ~[pc.class:?]
        at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:285) ~[gw.class:?]
        at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:180) [oz.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:1013) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:454) [nz.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:855) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:706) [MinecraftServer.class:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_191]
[11:15:55] [Server thread/INFO] [net.minecraft.server.network.NetHandlerLoginServer]: com.mojang.authlib.GameProfile@411fcdf6[id=d61967c5-0f78-4fae-a6b6-fd6e2115b599,name=pkj93184,properties={textures=[com.mojang.authlib.properties.Property@cf767c]},legacy=false] (/192.168.50.1:57147) lost connection: Internal server error
이렇게 떠요

이건 모드 종류입니다