Plugin Help Survival Games problem

Code:

[20:04:28] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'sg' in plugin SurvivalGames v0.5.8.54
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchCommand(CraftServer.java:624) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnection.handleCommand(PlayerConnection.java:1298) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnection.a(PlayerConnection.java:1158) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PacketPlayInChat.a(SourceFile:37) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PacketPlayInChat.a(SourceFile:9) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnectionUtils$1.run(SourceFile:13) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_80]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_80]
at net.minecraft.server.v1_9_R1.SystemUtils.a(SourceFile:45) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.D(MinecraftServer.java:679) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:361) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:635) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:539) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at java.lang.Thread.run(Unknown Source) [?:1.7.0_80]
Caused by: java.lang.NoSuchMethodError: org.bukkit.entity.Player.getMaxHealth()I
at org.mcsg.survivalgames.Game.addPlayer(Game.java:237) ~[?:?]
at org.mcsg.survivalgames.GameManager.addPlayer(GameManager.java:246) ~[?:?]
at org.mcsg.survivalgames.commands.Join.onCommand(Join.java:19) ~[?:?]
at org.mcsg.survivalgames.CommandHandler.onCommand(CommandHandler.java:164) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
... 15 more
[20:04:31] [pool-3-thread-15/INFO]: [SG]Checking for updates
[IMG]https://static.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:04:31] [pool-3-thread-15/WARN]: [SurvivalGames] [SurvivalGames] could not check for updates.
[IMG]https://static.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:04:37] [Server thread/WARN]: The save is being accessed from another location, aborting
[20:04:38] [Server thread/INFO]: ShyAway issued server command: /gamemode 1
[20:04:38] [Server thread/INFO]: [ShyAway: Set own game mode to Creative Mode]
[20:05:04] [Server thread/INFO]: ShyAway lost connection: Disconnected
[20:05:04] [Server thread/INFO]: ShyAway left the game.
[20:07:16] [Server thread/INFO]: dopeking1130 issued server command: /gamemode c
[20:07:16] [Server thread/INFO]: [dopeking1130: Set own game mode to Creative Mode]
[IMG]https://static.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:09:36] [Server thread/WARN]: The save is being accessed from another location, aborting
[20:11:30] [Server thread/INFO]: EddieEGL issued server command: /sg delete]
[20:11:34] [Server thread/INFO]: EddieEGL issued server command: /sg remove]
[20:11:38] [Server thread/INFO]: EddieEGL issued server command: /sg help
[20:11:48] [Server thread/INFO]: EddieEGL issued server command: /sg help 2
[20:12:14] [Server thread/INFO]: EddieEGL issued server command: /sg sart
[20:12:18] [Server thread/INFO]: EddieEGL issued server command: /sg start
[20:12:25] [Server thread/INFO]: EddieEGL issued server command: /sg join 1
[IMG]https://static.minecraft-hosting.pro/medias/severe.png[/IMG]
[20:12:25] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'sg' in plugin SurvivalGames v0.5.8.54
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchCommand(CraftServer.java:624) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnection.handleCommand(PlayerConnection.java:1298) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnection.a(PlayerConnection.java:1158) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PacketPlayInChat.a(SourceFile:37) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PacketPlayInChat.a(SourceFile:9) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.PlayerConnectionUtils$1.run(SourceFile:13) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_80]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_80]
at net.minecraft.server.v1_9_R1.SystemUtils.a(SourceFile:45) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.D(MinecraftServer.java:679) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:361) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:635) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:539) [craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
at java.lang.Thread.run(Unknown Source) [?:1.7.0_80]
Caused by: java.lang.NoSuchMethodError: org.bukkit.entity.Player.getMaxHealth()I
at org.mcsg.survivalgames.Game.addPlayer(Game.java:237) ~[?:?]
at org.mcsg.survivalgames.GameManager.addPlayer(GameManager.java:246) ~[?:?]
at org.mcsg.survivalgames.commands.Join.onCommand(Join.java:19) ~[?:?]
at org.mcsg.survivalgames.CommandHandler.onCommand(CommandHandler.java:164) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit-1.9-R0.1.jar:git-Bukkit-7fc5cd8]
... 15 more
[IMG]https://www.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:13:51] [pool-3-thread-17/WARN]: Exception in thread "pool-3-thread-17"
[IMG]https://www.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:13:51] [pool-3-thread-17/WARN]: org.apache.commons.lang.UnhandledException: Plugin Multiverse-Core v2.5-b699 generated an exception while executing task 805
at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at org.mcstats.multiverse.Metrics.postPlugin(Metrics.java:357)
at org.mcstats.multiverse.Metrics.access$400(Metrics.java:64)
at org.mcstats.multiverse.Metrics$1.run(Metrics.java:245)
at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:53)
at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 3 more
[IMG]https://www.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:13:51] [pool-3-thread-15/WARN]: Exception in thread "pool-3-thread-15"
[IMG]https://www.minecraft-hosting.pro/medias/warning.png[/IMG]
[20:13:51] [pool-3-thread-15/WARN]: org.apache.commons.lang.UnhandledException: Plugin SurvivalGames v0.5.8.54 generated an exception while executing task 807
at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at org.mcsg.survivalgames.Metrics.postPlugin(Metrics.java:365)
at org.mcsg.survivalgames.Metrics.access$500(Metrics.java:69)
at org.mcsg.survivalgames.Metrics$1.run(Metrics.java:257)
at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:53)
at org.bukkit.craftbukkit.v1_9_R1.schedul

 

Which plugin are you using exactly?

 

I'm confused. What exactly is the problem?