This is usually caused because the file is no longer stored on MediaFire. The key you provided for file access was invalid. If you find bugs then please let me know.Invalid or Deleted File. Making you constantly jump from unfinished feature to unfinished feature eventually turning your game into a mess of unfinished stuff. Be carefull of the temptation to add all kinds of cool stuff first as this might result in you constantly getting distracted with creating new features in the middle of making other ones.
Stay focused on your goal and key features and finish the most important things first. I would like to take this opportunity to give some advice to anyone who is making a game themselves: Ive finally finished an update for the GVB game.