Cant replace world with certain worlds

I've been playing on a world for two weeks and decided to purchase a 2 player realm so my brother could play on the same world when ever he wanted . But when ever i try and and upload the world to my realm it exports and then says initializing upload for a couple of minutes . After that it just says  FAILED an error occured. other worlds work .

the world size is 143mb . I think this is the problem