I have an error message pop up saying "There was a problem loading this world" every time I try to join a world.

I have an exported world because I originally had a world i spent 20+ hours on so i downloaded the world and uninstalled and reinstalled Minecraft to attempt and fix it. now every time i attempt and join the world a message pops up saying "There was a problem loading this world" ive tried every YouTube Video and everything but nothing works.