If Pokémon Go app is consistently notifying errors for uploading, there must be some problems with your connection or either you have overload on Pokémon Go server. If you see error again and again, try to disable and enable internet connection again and again. You can either try for upload some other time.
If it is failing in row try to use ispokemongodownornot.com in case servers are always found down. If you see CRIT written in boxes, this means other people trying to upload Pokémon Go are facing the same problem.
The servers are currently facing hard time to cope with overload on servers of Pokémon Go trainers across the world, try to refresh after 13-15 minutes.