Windows 10 user here! This issue has been going on since I tried to play last week and none of the steps listed in the help page to address this error have helped. The only time I can update, run the repair and scan function, or play Overwatch is while signed into the full admin account instead of my personal account that has all the same permissions. All files related to battle.net and Overwatch have my personal account set up with full admin rights (checked and changed manually just to make sure), my firewall has everything Blizzard may have even sneezed on listed in the ‘safe’ and ‘exception’ categories (turning off my antivirus doesn’t change anything), and none of my other programs and games have this issue.
This is incredibly frustrating, but in a hilarious take I somehow have enough rights to uninstall Overwatch but not update or reinstall it. Any help would be appreciated!