As I am not the only one who had that problem and I have not seen the solution been posted anywhere else, I hope you land here to find this:
- Uninstall the bnet app through Control Panel
- Go to Start->Search and type %APPDATA%
- Delete the Battle[.]net, Blizzard, and Blizzard Entertainment folders. If you don’t have all 3, just delete the ones you have. (same for AppData/Local)
- Repeat steps 2-3 with the following locations: %TEMP% , %LOCALAPPDATA% and %PROGRAMDATA%
- Download and install the latest version of the battle[.]net app
Credit goes to Game Master Poklatharne who gave me these steps in a bug ticket.