redscourge

I thought Tekkit required Java 1.7 not 1.6, have you tried upgrading and see if it goes away?

To answer the last question in this thread which wants to know exactly what files are involved and what to do, here is my explanation. First, you check the very top error message in the list that are shown, and you see that what failed was a bukkit file trying to access a part of "tried to access field net.minecraft.server.TileEntityMobSpawner.mobName", or in other words, the mobName function of the TileEntityMobSpawner class within the net.minecraft.server object, or in other words, the TileEntityMobSpawner.class file contained within the main jar file Tekkit.jar, and then within the net\minecraft\server\ subdirectory of that jar file. Therefore, here is how I fixed it: I downloaded CraftBukkit for 1.1.0-R4 from http://dl.bukkit.org/downloads/craftbukkit/view/00719_1.1-R4/ and then browsed the net\minecraft\server jar and copied TileEntityMobSpawner.class into my %appdata%\Tekkit_Server_2.1.1\Tekkit.jar in its net\minecraft\server subfolder. I use 7zip to browse the jar files and drag and drop files. Note: make a backup of your Tekkit.jar file before modding it! THIS THREAD NEEDS TO BE HIGHER IN THE GOOGLE SEARCH RESULTS! I bet it is very common that people get this error, because for example if you ever try to use the WorldEdit "//regen" command, it will often run into mob spawners and screw up. Either that, or somebody who develops Tekkit needs to replace this ONE class file within the jar file they are distributing with the tekkit pack.