I was having an issue with the error 404 on the about author page. My problem was the user name. I did not have a space, what I had was a period (.) in the middle of my username. This was causing the error 404. I could not change my username so I created another user name with a dash (-) instead of a period and gave that user admin privileges. Did a bulk edit on all my posts to change the author to the new profile. Now everything is working fine. No error 404.
