[13:30:54] [Server thread/ERROR]: Could not pass event PlayerJoinEvent to NaturaPVP v1.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.PlayerList.onPlayerJoin(PlayerList.java:298) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.PlayerList.a(PlayerList.java:157) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.LoginListener.b(LoginListener.java:144) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.LoginListener.c(LoginListener.java:54) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.NetworkManager.a(NetworkManager.java:231) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.ServerConnection.c(ServerConnection.java:148) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:814) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_72]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_8_R1/Packet
    at fr.crafttim.event.JoinEvent.onJoin(JoinEvent.java:14) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_72]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_72]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_72]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_72]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    ... 14 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_8_R1.Packet
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:91) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_72]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_72]
    at fr.crafttim.event.JoinEvent.onJoin(JoinEvent.java:14) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_72]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_72]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_72]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_72]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
    ... 14 more