Error log

Error log:

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2015-06-24 18:16:17 [SEVERE] Could not load 'plugins\UUIDForMinecraftLegacy.jar' in folder 'plugins':
java.lang.NoClassDefFoundError: org/bukkit/configuration/file/FileConfiguration
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:168)
	at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:213)
	at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:136)
	at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:138)
	at org.bukkit.craftbukkit.CraftServer.reload(CraftServer.java:408)
	at org.bukkit.Bukkit.reload(Bukkit.java:173)
	at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:22)
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:163)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:353)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:349)
	at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:503)
	at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:482)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)
Caused by: java.lang.ClassNotFoundException: org.bukkit.configuration.file.FileConfiguration
	at java.net.URLClassLoader.findClass(Unknown Source)
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:36)
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:24)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 16 more