https://www.gamespot.com/articles/fortnite-servers-go-offline-following-season-3-lau/1100-6456936/

Update: Epic has apologized for the downtime and announced that Fortnite's servers are back online. Along with that, you can now check out the new Season 3 content, including the latest Battle Pass, details of which are outlined below. The original story follows.

Following the launch of Fortnite's Season 3 update, servers for the game have been taken offline. According to the official Fortnite Twitter account, developer Epic Games is "currently investigating issues with this release" and needed to turn off servers as part of this. Since then, Epic has said it expects servers to be back at around 3 PM UK / 7 AM PST.