https://www.gamespot.com/articles/fortnite-season-6-release-date-confirmed-last-chan/1100-6461788/

We're now in the final days of Fortnite Season 5, which means a whole new season and other big changes are just around the corner for the popular battle royale game. (Already, we've seen the cube meet its end.) That also means this is your last opportunity to complete Season 5 challenges and unlock any remaining Battle Pass rewards if you still haven't on PS4, Xbox One, PC, Nintendo Switch, and mobile. [Update: Season 6 officially begins on September 27.]

As it has done in previous seasons, Epic released 10 weekly batches of challenges for players to complete throughout Season 5. For this season, the tasks were divided up into two categories--Free and Battle Pass--so even those who haven't purchased a Battle Pass, which was typically the only way to gain access to the challenges, could be able to complete some and earn rewards.