Sever crash

[warmanjr2]

Server crashing when more than one person is on gives this error. What could be the issue?

 

26.03 18:28:47 [server] WARNING Tiles Last Tick: 0
26.03 18:28:47 [server] WARNING Entities Last Tick: 0
26.03 18:28:47 [server] WARNING Loaded Chunks: 0 Active Chunks: 0 Entities: 0 Tile Entities: 0
26.03 18:28:47 [server] WARNING Dimension:9
26.03 18:28:47 [server] WARNING Tiles Last Tick: 0
26.03 18:28:47 [server] WARNING Entities Last Tick: 0
26.03 18:28:47 [server] WARNING Loaded Chunks: 0 Active Chunks: 0 Entities: 0 Tile Entities: 0
26.03 18:28:47 [server] WARNING Dimension:21
26.03 18:28:47 [server] WARNING Tiles Last Tick: 362
26.03 18:28:47 [server] WARNING Entities Last Tick: 105
26.03 18:28:47 [server] WARNING Loaded Chunks: 461 Active Chunks: 117 Entities: 134 Tile Entities: 544
26.03 18:28:47 [server] WARNING Dimension:0
26.03 18:28:47 [server] WARNING [TPS]: 20.0 Server Tick #18170
26.03 18:28:47 [server] WARNING Last Tick: 1395872904995 Current Time: 1395872927058 Warning: 20000 Timeout: 60000
26.03 18:28:47 [server] WARNING The server is going slow. Last server tick was 22064ms ago
26.03 18:28:44 [server] INFO               
26.03 18:28:44 [Multicraft] Skipped 15 lines due to rate limit (30/s)
26.03 18:28:25 [server] SEVERE at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:663)
26.03 18:28:25 [server] SEVERE at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:781)
26.03 18:28:25 [server] SEVERE at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:330)
26.03 18:28:25 [server] SEVERE at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:918)
26.03 18:28:25 [server] SEVERE at net.minecraft.server.management.ServerConfigurationManager.func_72374_b(ServerConfigurationManager.java:1125)
26.03 18:28:25 [server] SEVERE at java.util.ArrayList.get(Unknown Source)
26.03 18:28:25 [server] SEVERE at java.util.ArrayList.elementData(Unknown Source)
26.03 18:28:25 [server] SEVERE java.lang.ArrayIndexOutOfBoundsException: -1
26.03 18:28:25 [server] INFO Sending serverside check to:
26.03 18:28:25 [server] INFO Loading Player:

Edited March 26, 2014 by warmanjr2

[Loader]

There's not enough info there to really be sure, but if you're using MCPC+ then it's probably this;

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In future, please post this kind of thing up on the issue tracker (there's a link in my sig or at the top of the page).