seems that you had a space at the end of your mysql name : john @localhost should be john@localhost , verify your db.ini for a possible space at the end of your name
actually I tried with addind a space at the end of my mysqlusername and I got the same error so thats it , just remove the space.
(if a coder see that , could you add a trim to the name and password reading , it would remove some errors like that
)