Could not get information about this CraftBukkit version

[TheArmyKing10]

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.

[Kalbintion]

Craftbukkit will not work for modpacks btw, you wouldve needed cauldron. Either way, both were taken down due to the DMCA requests, and unless you got it before the DMCA request, it may not be a valid source of craftbukkit and cannot be guaranteed to work, be current, or anything of the sort.