java.util.ConcurrentModificationException
[05:20:49 WARN]: at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
[05:20:49 WARN]: at java.util.HashMap$ValueIterator.next(HashMap.java:1458)
[05:20:49 WARN]: at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75820_a(AnvilChunkLoader.java:388)
[05:20:49 WARN]: at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75816_a(AnvilChunkLoader.java:218)
[05:20:49 WARN]: at net.minecraft.world.gen.ChunkProviderServer.func_73242_b(ChunkProviderServer.java:358)
[05:20:49 WARN]: at net.minecraft.world.gen.ChunkProviderServer.func_73156_b(ChunkProviderServer.java:503)
[05:20:49 WARN]: at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:261)
[05:20:49 WARN]: at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:931)
[05:20:49 WARN]: at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:431)
[05:20:49 WARN]: at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:809)
[05:20:49 WARN]: at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:669)
[05:20:49 WARN]: at java.lang.Thread.run(Thread.java:745)