Hello.
I came to an issue, where if you catch any mob in one world (it is Multiverse generated), you can not "deploy" or "spawn" the mob again. It sends this error instead:

[19:47:42] [Server thread/FATAL] [net.minecraft.server.MinecraftServer]: Error executing task java.util.concurrent.ExecutionException: java.lang.NoClassDefFoundError: com/mojang/realmsclient/gui/ChatFormatting at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_171] at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_171] at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:919) [MinecraftServer.class:?] at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:461) [nz.class:?] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:858) [MinecraftServer.class:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:730) [MinecraftServer.class:?] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171] Caused by: java.lang.NoClassDefFoundError: com/mojang/realmsclient/gui/ChatFormatting at me.marnic.animalnet.common.item.ItemCaughtEntity.sendError(ItemCaughtEntity.java:164) ~[ItemCaughtEntity.class:?] at me.marnic.animalnet.common.item.ItemCaughtEntity.func_180614_a(ItemCaughtEntity.java:134) ~[ItemCaughtEntity.class:?] at net.minecraftforge.common.ForgeHooks.onPlaceItemIntoWorld(ForgeHooks.java:839) ~[ForgeHooks.class:045a413] at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:210) ~[aip.class:?] at net.minecraft.server.management.PlayerInteractionManager.func_187251_a(PlayerInteractionManager.java:590) ~[or.class:?] at net.minecraft.network.NetHandlerPlayServer.func_184337_a(NetHandlerPlayServer.java:1141) ~[pa.class:?] at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.func_148833_a(SourceFile:55) ~[ma.class:?] at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.func_148833_a(SourceFile:11) ~[ma.class:?] at net.minecraft.network.PacketThreadUtil.lambda$checkThreadAndEnqueue$0(PacketThreadUtil.java:14) ~[hv.class:?] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_171] at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_171] at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?] ... 5 more

Any help? Might it be cuz of the world being created using the Multiverse plugin?