Seems that people are encountering glitches where Pokemon X/Y will crash when saving in Lumiose City. Trying to load the game back up results in the game crashing again, meaning as of now, the only option is to reset your game if you encounter the glitch. It seems the glitch only occurs in the outside portion of the city, and buildings are fine. But I'd recommend staying away from the city or saving anywhere in it for the time being.
http://www.gamepur.c...tside-lumi.html