Full server crash when fighting other players, it crashes after the battle is over and the results screen is supposed to show up. Server just stops and says "Server closed".

java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/api/enums/BattleResults
at com.nguyenquyhy.PixelmonFriends.events.PixelmonEventHandler$1.<clinit>(PixelmonEventHandler.java:66) ~[PixelmonEventHandler$1.class:?]
at com.nguyenquyhy.PixelmonFriends.events.PixelmonEventHandler.battleEnded(PixelmonEventHandler.java:66) ~[PixelmonEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_48_PixelmonEventHandler_battleEnded_PlayerBattleEndedEvent.invoke(.dynamic) ~[?:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:635) ~[EventBus.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:591) ~[EventBus.class:?]
at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.endBattle(BattleControllerBase.java:675) ~[BattleControllerBase.class:?]
at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.checkDefeated(BattleControllerBase.java:1118) ~[BattleControllerBase.class:?]
at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.checkPokemon(BattleControllerBase.java:1046) ~[BattleControllerBase.class:?]
at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.update(BattleControllerBase.java:352) ~[BattleControllerBase.class:?]
at com.pixelmonmod.pixelmon.battles.BattleRegistry.updateBattles(BattleRegistry.java:138) ~[BattleRegistry.class:?]
at com.pixelmonmod.pixelmon.battles.BattleTickHandler.tickStart(BattleTickHandler.java:12) ~[BattleTickHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_36_BattleTickHandler_tickStart_WorldTickEvent.invoke(.dynamic) ~[?:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:635) ~[EventBus.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:591) ~[EventBus.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onPostWorldTick(FMLCommonHandler.java:269) ~[FMLCommonHandler.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:718) ~[MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:387) ~[ld.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471) [MinecraftServer.class:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45]
Caused by: java.lang.ClassNotFoundException: com.pixelmonmod.pixelmon.api.enums.BattleResults
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_45]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_45]
... 22 more
Caused by: java.lang.NullPointerException
[15:30:13] [Server thread/ERROR]: This crash report has been saved to: /home/gameservers/services/service12167/files/./crash-reports/crash-2017-04-06_15.30.13-server.txt
[15:30:13] [Server thread/INFO]: Stopping server
[15:30:13] [Server thread/INFO]: Saving players
[15:30:13] [Server thread/INFO]: Saving worlds