Killerdodo1234

Try updating java. I know that also caused problems for me. If that doesn't work, try redownloading the launcher again. I just got mine today, but I don't know any other reason for it not working.

Did you do everything I said. I know I had that same problem. I updated it. You have to delete and reinstall the techniclauncher folder, because some of it has changed to make 1.2.5 work properly.

I think I know the answer to your problem, As I had it as well. Try this: Click on the start button, then type "%appdata%". If not using windows 7, use "run" and type the same thing. Back up all of the modpacks from ".techniclauncher" onto a seperate except for tekkit. delete ".techniclauncher" and ".minecraft". UPDATE YOUR TECHNIC LAUNCHER. This is the main problem. Now, re-install tekkit, and drag in you other modpacks again. This should resolve the error. I now see you are on a mac. Go to you techniclauncher folder and do the same as above. The problem is that the launcher.jar or whatever you are using needs to be updated to work properly.

I believe the problem is that it is launching it from .Minecraft, and not the tekkit folder it .techniclauncher. I deleted my .Minecraft, and it came back when loading it again.