Facebook announced the return of F8 developer event in a virtual-only format this time and renamed it F8 Refresh. The one-day event is scheduled to happen on June 2. Click here to sign up for F8 Refresh. F8 typically attracts around 5,000 developers across the globe every year. Media reports said that Facebook CEO Mark Zuckerberg will not deliver keynote this year. It is still not sure if he will be making an appearance at all.