A null session in Sburb is any session of the game that is doomed to failure. While this refers to any session that fails to create a universe, it also seems to refer to sessions where the players create a universe but are still unable to win. Both Karkat Vantas and Aradia Megido call their own session a null session after Jack Noir prevented them from obtaining the Ultimate Reward, even though they successfully created a universe and killed the Black King. The Session Glitch is hinted to create a null session.