Game Crashes from old worlds

The old worlds in our Minecraft games seem to be crashing the game. The game only allows us to login in to an old world for about 15 seconds then it will crash and go to the home screen of the device being played on. All of the newly created ones are perfect and work. Please fix this... Some of these old worlds are very valuable to the community.

 

I will provide video bellow. Video cut in fourths due to size problems.