The login servers received invalid information
Information about this error when trying to log in
A community site or app throws a 404 error when attempting to login via B.net or when accessing your Battle.net data.
What to do if you cannot log in to Hearthstone with your Battle.net account email on a mobile device
How to resolve this error when trying to log in to Battle.net
Troubleshooting for error "Too many attempts" when trying to log in to the Blizzard website
What to do when the Battle.net Desktop App won't let you stay logged in
Information on logging into the Battle.net application on more than one computer
Using LogGoblin to gather Battle.net desktop app logs.