12:18:28 [INFO] Connection reset
12:18:28 [SEVERE] java.util.ConcurrentModificationException
12:18:28 [SEVERE]       at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
12:18:28 [SEVERE]       at java.util.AbstractList$Itr.next(AbstractList.java:343)
12:18:28 [SEVERE]       at java.util.AbstractCollection.removeAll(AbstractCollection.java:336)
12:18:28 [SEVERE]       at net.minecraft.server.World.tickEntities(World.java:1197)
12:18:28 [SEVERE]       at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:545)
12:18:28 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452)
12:18:28 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(SourceFile:490)
12:18:28 [SEVERE] Unexpected exception
java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
        at java.util.AbstractList$Itr.next(AbstractList.java:343)
        at java.util.AbstractCollection.removeAll(AbstractCollection.java:336)
        at net.minecraft.server.World.tickEntities(World.java:1197)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:545)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:490)
12:18:29 [INFO] Connection reset
12:18:40 [INFO] Connection reset