Solved What Does This Mean?

21:40:50 [SEVERE] Could not load 'plugins/sEssentials.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: sEssentials/sEssentials : Unsupported major.minor version 51.0
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:184)
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugins(CraftServer.java:239)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.reload(CraftServer.java:607)
at org.bukkit.Bukkit.reload(Bukkit.java:277)
at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:23)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:192)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.dispatchCommand(CraftServer.java:523)
at net.minecraft.server.v1_6_R3.PlayerConnection.handleCommand(PlayerConnection.java:959)
at net.minecraft.server.v1_6_R3.PlayerConnection.chat(PlayerConnection.java:877)
at net.minecraft.server.v1_6_R3.PlayerConnection.a(PlayerConnection.java:834)
at net.minecraft.server.v1_6_R3.Packet3Chat.handle(SourceFile:49)
at net.minecraft.server.v1_6_R3.NetworkManager.b(NetworkManager.java:296)
at net.minecraft.server.v1_6_R3.PlayerConnection.e(PlayerConnection.java:116)
at net.minecraft.server.v1_6_R3.ServerConnection.b(SourceFile:37)
at net.minecraft.server.v1_6_R3.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_6_R3.MinecraftServer.t(MinecraftServer.java:592)
at net.minecraft.server.v1_6_R3.DedicatedServer.t(DedicatedServer.java:227)
at net.minecraft.server.v1_6_R3.MinecraftServer.s(MinecraftServer.java:488)
at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:421)
at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.UnsupportedClassVersionError: sEssentials/sEssentials : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:249)
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)

... 21 more

 

You are compiling a plugin with Java 7 and running a server with java 6.

 

That plugin was compiled with Java 7, you need to be running Java 7 or higher.

Edit: Ninja'd.

 

OH, I need Java 6

 

No, you actually need Java 7. The error is because the plugin was compiled with a newer version, not that you're using a newer version.

 

NinjaWAffles
Wait, I'm confused now...

I have 3 other plugins that are exactly the same but they work...

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

The plugin was compiled with Java 7 and you're running Java 6, so you need to update to Java 7. You can just get it off of Oracle's website.

Run your server with Java 7.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

NinjaWAffles
How do I make my plugin Java 6?

Wait nvm I found it...

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

If you're making a new project, change "Use an execution path environment" to "Java-SE1.6"; if you're editing an existing plugin, go to Properties --> Java Compiler --> Set 'Compiler Compliance Level' to 1.6.