19:12:40 [SCHWERWIEGEND] Could not load 'plugins/GameModeChanger_v1.1.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: net/pirategaming/gmd/Gmd : Unsupported major.minor version 51.0
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:154)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:222)
        at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:198)
        at net.minecraft.server.ServerConfigurationManagerAbstract.<init>(ServerConfigurationManagerAbstract.java:50)
        at net.minecraft.server.ServerConfigurationManager.<init>(SourceFile:11)
        at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:105)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:378)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.lang.UnsupportedClassVersionError: net/pirategaming/gmd/Gmd : 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:44)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:29)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:264)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:143)
        ... 9 more
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