[https://forum.defcon.org/]
The DEF CON forum is temp down for a complete rebuild, from hardware to software.
Nothing has been lost but enough upgrades over the many years and an email bug that prevented new signups from happening was the final straw. Time to start over.
Because DEF CON 26 is so close I'm not confident this will hapen before con, but it is starting to be worked on. Updates will follow here.
The Dark Tangent