When i update my btw version to A7 Squid, the minecraft do'nt recognize the save from A6, i can create a new world, and play on it without any problem, but the game can't even understand that the folder with the old map is a save (does not appear in the worlds selection screen).
P.s The world is not corrupted cause still works fine at the A6.
P.S 2 Im using the game with MCPatcher, and the the folder disappear cause of the level.dat.
[EDIT] Sorry guys, my mistake...my map corrupted, I do not know if it was something from the new update (probably not) it turned out that what was working was backing up a week ago (yes I missed a week of game = /). So no bug here, sorry again