---- Minecraft Crash Report ----
// Why did you do that?

Time: 3/3/16 4:41 PM
Description: Exception in server tick loop

java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
	at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
	at java.util.AbstractCollection.addAll(AbstractCollection.java:343)
	at sq.c(SourceFile:62)
	at id.<init>(SourceFile:26)
	at lt.d(SourceFile:304)
	at lt.a(SourceFile:243)
	at lm.a(SourceFile:196)
	at net.minecraft.server.MinecraftServer.D(SourceFile:633)
	at la.D(SourceFile:339)
	at net.minecraft.server.MinecraftServer.C(SourceFile:553)
	at net.minecraft.server.MinecraftServer.run(SourceFile:457)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 1.9
	Operating System: Linux (amd64) version 3.13.0-71-generic
	Java Version: 1.8.0_72, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 1994042880 bytes (1901 MB) / 5261230080 bytes (5017 MB) up to 7470055424 bytes (7124 MB)
	JVM Flags: 0 total; 
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Player Count: 4 / 20; [lr['Point4link'/1318086, l='world', x=1116.16, y=69.00, z=-1345.81], lr['TheStreets01'/1491526, l='world', x=-3840.40, y=71.00, z=-2563.44], lr['UltimateDevilbat'/1523999, l='world', x=438.68, y=64.80, z=1775.64], lr['JianIsMEEEE'/1517690, l='world', x=-419.77, y=67.00, z=413.79]]
	Is Modded: Unknown (can't tell)
	Type: Dedicated Server (map_server.txt)