What do these errors mean?

So i wrote a plugin, and on my server it worked perfectly.

Here is the Error:

Code:

13:57:30 [SEVERE] Could not load 'plugins\ezdonor.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError
: us/rivertech/ezdonor/ezDonor : Unsupported major.minor version 51.0
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava: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:227)
    at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:205)
    at net.minecraft.server.ServerConfigurationManagerAbstract.<init>(Server
ConfigurationManagerAbstract.java:51)
    at net.minecraft.server.ServerConfigurationManager.<init>(SourceFile:11)
 
    at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:111)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:398)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)
Caused by: java.lang.UnsupportedClassVersionError: us/rivertech/ezdonor/ezDonor
: Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    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(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava:143)
    ... 9 more 

Any ideas on what this means, or what it could be, and if it is the plugin or the server? I can give more information or the code if needed.

 

You compiled against Java 7, while your server is using Java 6. Just use Java 6 as there are a lot of servers using that

 

so for the JRE use Java 6, i was using 7 on my server and it worked fine, i was getting complaints this was happening.

 

you should use JDK 6 to compile. I am not talking about JRE

 

Ohhhh! Ok, Thank you. So i can use JRE 7 in eclipse, i just need to compile with JDK 6?

 

yes

 

when i go window > prefrences > copiler > then choose 1.6 that is the same as JDK 6, and 1.7 is the same as jdk 7 or?

 

Yes you can just change to 1.6

You can do it this way..

or right click your plugin name and then select build path, and configure build path then double click the jre to change it