Crash report

Hello,

I had a crash this morning. What does this kind of error?

Code:

Description: Exception in server tick loop
 
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:782)
at java.util.ArrayList$Itr.next(ArrayList.java:754)
at net.minecraft.server.EntityTrackerEntry.track(EntityTrackerEntry.java:85)
at net.minecraft.server.EntityTracker.updatePlayers(EntityTracker.java:136)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:586)
at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:493)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)

 

Could you at least put the whole report in?

 

It is too long

 

Use pastebin: http://pastebin.com/

 

http://pastebin.com/SDKiWGT3

 

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