Mod talk:TEdit/@comment-25849682-20141211033707/@comment-10898177-20141212121053

You'll need to get a version of TEdit that is prior to 3.5.14228.27 (the latest), since Terraria 1.2.4 changed the world code and so TEdit had to ajust accordingly. TEdit for 1.2.1 worked with 1.2.2 and 1.2.3 worlds for me, so I suggest looking for that. It seems that the version you have should work. Word or warning, though: If you open a 1.2.2 world with any version of TEdit designed for 1.2.4, it will crash. And if you accidentally open a 1.2.2 world with Terraria 1.2.4, it will recode the world for the new format and the world will no longer work with older versions or TEdit or Terraria.

Interestingly enough, the GitHub "latest version" is very out-of-date. The Binary Construct website has the latest installer.