Few things to try:
  • Close the game, go to Documents\My Games\Final Fantasy XIV - A Realm Reborn, move all the CHAR folders somewhere else (but keep them somewhere as a backup). Start the game. It will reset all your hotbars, HUD Layout and macros, but it sometimes fixes the crash if one of these files is corrupted.
  • Go to C:\Program Files (x86)\SquareEnix\FINAL FANTASY XIV - A Realm Reborn\game\sqpack, open each folder one at a time, attempt to copy+paste each individual patch file to another location (you can cancel after it). If it fails, then the data is corrupted (particularly common on an SSD due to a cylinder failing).
  • If the crash is related to a specific location, you can right-click your character and press Visit Another World Server. It will put you on a different server but in Ul'dah. You can return to your homeworld by clicking the aetheryte.