Version 3.2.1.7 of Terraria GameLauncher for Terraria 1.2.4.1 from Tool - Game Launcher 3.2.1.5.Until then, please read through the replies.
I haven't tried if any of those work myself, but once I will I might update the guide. For Information on how to fix that, please look in the replies of this post. Most of this guide probably still works, but apparently Steam changed the way their Depots work a little bit.