world size buff

MOJANG I have to tell you I worked on a world for 5 years on pure survival and I can't even sync it to the better together update it was fine when I moved it from the 360 to the Xbox one when the one came out I still had the same world jump to get minecraft to just keep building my minecraft city I been DYING TO GET THE BETTER TOGETHER update to work for me it won't sync my world that so over 314.1 MB it's gets so close to the 100% line then everything goes black and then I get a error code 0x87b20c08 every time and then after that I try to open up my guild menu and I get the error code again and again and then sometime I do get my guild menu I try government report a problem to XBOX IT SELF And I get an error code for trying to report that error I don't get it I really don't I have to restart my Xbox every day to see if I can update my world finally but no I try and then I get black screen then error code then nothing else works ... mojang I need your help I love minecraft but I can't start all over because I can't get my world to sync 5 long years I worked on it and it would be really sad to stop it because of the better together update ... btw I can sync my worlds that are lower then 20.5 MB but anything higher doesn't sync