Bukkit

When i try to add someone as a friend i get this in my chat

An internal error occurred while attempting to perform this command.

Console logs:

Caused by: java.lang.ClassNotFoundException: org.bukkit.craftbukkit.libs.com.google.gson.Gson

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.loadClassHelper(ClassLoader.java:946) ~[?:1.8.0_212]

at java.lang.ClassLoader.loadClass(ClassLoader.java:891) ~[?:1.8.0_212]

at java.lang.ClassLoader.loadClass(ClassLoader.java:874) ~[?:1.8.0_212]

at com.mojang.auth.HttpProfileRepository.<clinit>(HttpProfileRepository.java:16) ~[?:?]

at me.CopyableCougar4.main.MineUUID.<clinit>(MineUUID.java:11) ~[?:?]

at me.CopyableCougar4.main.FriendMeEvents.onJoin(FriendMeEvents.java:47) ~[?:?]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_212]

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_212]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_212]

at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_212]

at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[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]

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