Gmail Add another email address you own Authentication failed even if the password is correct

Did you encounter this error even if your password is correct? “Authentication failed. Please check your username/password. [Server response: 534-5.7.14 Please log in via your web browser and 534-5.7.14 then try again. 534-5.7.14 Learn more at 534 5.7.14 m3sm2558931lfb.8 – gsmtp code(534) ]” Then you’ve come to the right place.