https://www.gamespot.com/articles/where-are-fortnites-week-9-challenges/1100-6461551/

Update 2: The new High Stakes update, version 5.40, is live; it makes a number of balance changes and introduces the limited-time High Stakes mode. You can now dive into that and its accompanying challenges, but you'll have to wait for the proper Week 9 challenges. Those are due to launch on Friday, September 7. Check back for full guides on how to complete them soon. The original story follows.

Fortnite's recently teased High Stakes event is coming a little later than planned. Developer Epic Games announced on Twitter that the event--along with the 5.40 update--will now roll out for PC, PS4, Xbox One, Nintendo Switch, and mobile on Thursday, September 6, which will also delay the arrival of Week 9's challenges. [Update: Epic has confirmed the update is all set for launch on Thursday. Before you can dive in, servers will go down at 1 AM PT / 4 AM ET / 9 AM BST; we don't yet know how long that will take, but there should be a lot of new things to dig into once things come back online.]