Microsoft has announced that Xbox FanFest registration re-opens on April 26th

After having some technical problems, causing the system to accept more registrants than they had tickets for the event in total on April 19, 2017 with the Xbox FanFest registration Microsoft have announced a new date to get tickets. Instead of doing different waves of 100 during certain times of the day they will be dropping 400 of 500 all at once at 9 AM PDT April 26th.
“We are happy to announce a new date and time for Xbox FanFest: E3 2017 ticket online registration.  To ensure all fans have enough time to plan for this moment, we’re scheduling it next week on Wednesday, April 26th at 9am PT.  To streamline our approach after yesterday’s error, all 400 tickets will be available, all at once, starting at 9am PT.  Tickets remain first-come, first-serve, one ticket per-person.  Additionally, all requirements (21+ years old, credit card required to hold) remain exactly the same. “
Keep an eye out for Xbox’s twitter account for a link.