---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 5/11/16 11:18 PM
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: java/util/concurrent/ForkJoinTask
	at it.unimi.dsi.fastutil.longs.LongArraySet.<init>(LongArraySet.java:99)
	at net.minecraft.server.v1_9_R2.ChunkProviderServer.<init>(ChunkProviderServer.java:26)
	at net.minecraft.server.v1_9_R2.WorldServer.n(WorldServer.java:845)
	at net.minecraft.server.v1_9_R2.WorldServer.<init>(WorldServer.java:66)
	at net.minecraft.server.v1_9_R2.MinecraftServer.a(MinecraftServer.java:273)
	at net.minecraft.server.v1_9_R2.DedicatedServer.init(DedicatedServer.java:268)
	at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:532)
	at java.lang.Thread.run(Thread.java:701)
Caused by: java.lang.ClassNotFoundException: java.util.concurrent.ForkJoinTask
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
	... 8 more


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: 1.9.4
	Operating System: Linux (amd64) version 3.2.0-4-amd64
	Java Version: 1.6.0_38, Sun Microsystems Inc.
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 473150664 bytes (451 MB) / 514523136 bytes (490 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 3 total; -Xms512M -Xmx1024M -XX:MaxPermSize=128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	CraftBukkit Information: org.bukkit.craftbukkit.v1_9_R2.CraftCrashReport@512d467f
	Profiler Position: N/A (disabled)
	Player Count: 0 / 5; []
	Is Modded: Definitely; Server brand changed to 'Spigot'
	Type: Dedicated Server (map_server.txt)