Arvetis

Well, I fixed it for myself. I think the problem was that I had several versions of Java installed at the same time. I went into Programs and Features in the Control Panel, removed all Java versions, rebooted, reinstalled the latest version of Java, then reinstalled the Technic launcher. It seems to be working now.

I get the exact same error message with the Jenkins build.

I have this exact same problem as well, but I suspect that it might be a launcher problem rather than a Tekkit Classic problem, since it seems to happen for all of my Technic addon packs. If that's the case for you as well, per the sticky in this forum, you may want to post about this in the launcher bugs forum rather than here. Either way, someone let me know if there's a solution for this!