Issues with Tekkit Server 3.0.4

[Steeled]

I recently tried starting a Tekkit Server, I watched tutorials and guides and such and have hosted many servers in the past. I get this strange error when trying to launch the tekkit server, something about nether ores? I'll post it:

C:\Users\Sean\Desktop\Tekkit Server>java -Xmx3G -Xms2G -jar Tekkit.jar nogui

182 recipes

27 achievements

17:15:21 [iNFO] Starting minecraft server version 1.2.5

17:15:21 [iNFO] Forge Mod Loader version @MAJOR@.@MINOR@.@REV@.@BUILD@ for Minec

raft @MCVERSION@ loading

17:15:21 [iNFO] Loading mods from C:\Users\Sean\Desktop\Tekkit Server\mods

17:15:21 [sEVERE] java.lang.UnsupportedClassVersionError: net/minecraft/server/m

od_NetherOres : Unsupported major.minor version 51.0

17:15:21 [sEVERE] at java.lang.ClassLoader.defineClass1(Native Method)

17:15:21 [sEVERE] at java.lang.ClassLoader.defineClassCond(Unknown Source)

17:15:21 [sEVERE] at java.lang.ClassLoader.defineClass(Unknown Source)

17:15:21 [sEVERE] at java.security.SecureClassLoader.defineClass(Unknown S

ource)

17:15:21 [sEVERE] at java.net.URLClassLoader.defineClass(Unknown Source)

17:15:21 [sEVERE] at java.net.URLClassLoader.access$000(Unknown Source)

17:15:21 [sEVERE] at java.net.URLClassLoader$1.run(Unknown Source)

17:15:21 [sEVERE] at java.security.AccessController.doPrivileged(Native Me

thod)

17:15:21 [sEVERE] at java.net.URLClassLoader.findClass(Unknown Source)

17:15:21 [sEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)

17:15:21 [sEVERE] at sun.misc.Launcher$AppClassLoader.loadClass(Unknown So

urce)

17:15:21 [sEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)

17:15:21 [sEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)

17:15:21 [sEVERE] at java.lang.Class.forName0(Native Method)

17:15:21 [sEVERE] at java.lang.Class.forName(Unknown Source)

17:15:21 [sEVERE] at cpw.mods.fml.common.Loader.loadModClass(Loader.java:4

40)

17:15:21 [sEVERE] at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.jav

a:497)

17:15:21 [sEVERE] at cpw.mods.fml.common.Loader.load(Loader.java:375)

17:15:21 [sEVERE] at cpw.mods.fml.common.Loader.loadMods(Loader.java:527)

17:15:21 [sEVERE] at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBuk

kitHandler.java:113)

17:15:21 [sEVERE] at net.minecraft.server.MinecraftServer.init(MinecraftSe

rver.java:118)

17:15:21 [sEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftSer

ver.java:426)

17:15:21 [sEVERE] at net.minecraft.server.ThreadServerApplication.run(Sour

ceFile:492)

17:15:21 [sEVERE] Unexpected exception

java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Un

supported 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 java.lang.ClassLoader.loadClass(Unknown Source)

at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)

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 cpw.mods.fml.common.Loader.loadModClass(Loader.java:440)

at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.java:497)

at cpw.mods.fml.common.Loader.load(Loader.java:375)

at cpw.mods.fml.common.Loader.loadMods(Loader.java:527)

at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBukkitHandler.java:

113)

at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)

at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)

>

Well, there you go. If you have any idea whats wrong and if I can fix it, please let me know.

[Backplague]

Remove all versions of Java you may have and get Java 7, download link can be found at technicpack.net.

[Steeled]

Thanks, I'll try that now.

Is changing enviromental variables a required thing?

[Steeled]

Ok I think I see where the problem was. I had 6 different versions of Java on my computer (I used to do a lot of Java stuff back in the day LOL) so I deleted them all, and installed the newest version of Java 7 x64. I looked at my enviromental variables, and the "PATH" one was set to a very old version of Java. I fixed the enviromental variables and now it worked. Let this be a lesson to all you others having issues out there. I'll lock this thread.