Hello guys, I have almost the same issue on Xbox One, I was able to upload any world without problems, but once I used a custom resource pack in a world, I couldn't upload it, even if I removed the resource pack.
It showed the same message "An error has ocurred".
It says "level export started", then "level export finished succesfully, then it keeps loading for some minutes, and a window pops up saying that an error ocurred.
Hello guys, I have almost the same issue on Xbox One, I was able to upload any world without problems, but once I used a custom resource pack in a world, I couldn't upload it, even if I removed the resource pack.
It showed the same message "An error has ocurred".