Windows .jar Some server commands don't work.

[incertia]

Namely /help.
The server just spits out

2014-01-13 20:18:04 [INFO] [Minecraft-Server] An unknown error occurred while attempting to perform this command
2014-01-13 20:18:04 [INFO] [STDERR] java.lang.IllegalArgumentException: Comparison method violates its general contract!
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.ComparableTimSort.mergeHi(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.ComparableTimSort.mergeAt(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.ComparableTimSort.mergeCollapse(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.ComparableTimSort.sort(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.ComparableTimSort.sort(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.Arrays.sort(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at java.util.Collections.sort(Unknown Source)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.command.CommandHelp.func_71534_d(SourceFile:74)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.command.CommandHelp.func_71515_b(SourceFile:36)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.command.CommandHandler.func_71556_a(CommandHandler.java:88)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.server.dedicated.DedicatedServer.func_71333_ah(DedicatedServer.java:315)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:277)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:587)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484)
2014-01-13 20:18:04 [INFO] [STDERR]  at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)

 

[incertia]

bumpity bump

 

[traumatism]

Same query about why this is from me