World formats change between updates of the game. So you can't use a world that was last opened in version 1.1 with version 1.2.4 of the game.
1.Junk-Jack-Wiki 2. The world is big, 256 blocks high and 768 across. 3. Who is John Galt? 4. Lack of objection does not indicate consent. 5. We scream, we shout, we wail, we cry; but in the end we all must die.