hi I haven't played in a while on mc so I decided to update the app and go to an old world as soon as I tried to open the world it crashed the app I have tried this with multiple worlds and get the same result I thought a pc might help so I imported it to win 10 version and even that crashes.
I also tried this on my iPad pro 2017 with my old worlds on it and it crashed too
if I'm correct the conversion code cant convert my worlds and this seems to be a bug with all versions of Minecraft (mc win 10 , iOS , android)