19:57:15 [SEVERE] Could not load 'plugins/RecipeManager.jar' in folder 'plugins': 
java.lang.UnsupportedClassVersionError: digi/recipeManager/RecipeManager : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        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(ClassLoader.java:321)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:264)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:170)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:215)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:136)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:136)
        at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:112)
        at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigurationManager.java:52)
        at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:136)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:348)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)