when i start my server, on the console says
11:59:00 [VARNING] Could not get information about this CraftBukkit version; perhaps you are running a custom one?: IOException
11:59:00 [VARNING] Could not get latest artifact information: IOException
and then some of my plugins does not wanna load like for example:
11:59:00 [ALLVARLIG] Could not load 'plugins/InventoryKits.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: main/InventoryKits : 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:241)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.<init>(CraftServer.java:219)
at net.minecraft.server.v1_6_R3.PlayerList.<init>(PlayerList.java:56)
at net.minecraft.server.v1_6_R3.DedicatedPlayerList.<init>(SourceFile:11)
at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:107)
at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:393)
at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.UnsupportedClassVersionError: main/InventoryKits : 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)
... 9 more
and it says the same on rest of my plugins... please help me i try to fix this but no work ... im using craftbukkit version 1.6.2 R2.0.