https://www.gamespot.com/articles/world-of-warcraft-battle-for-azeroth-is-live-but-s/1100-6461130/

Update: Blizzard has officially launched Battle for Azeroth, and you might be able to play the new WoW content right now. However, if you weren't already logged in, you may find you have trouble doing so--players are reporting issues getting online. Some of us here at GameSpot are stuck at a "logging in to game server" screen (pictured below), while other players say they're getting in only to be unable to see their characters. That's presumably just a hiccup as Blizzard's servers are slammed with people trying to get online, but it's nonetheless a frightening prospect to face.

Blizzard acknowledged at least one problem, saying on its customer support Twitter account, "We're currently investigating an issue affecting our authentication servers, which may result in failed or slow login attempts." It's unclear how long it will take for all of this to be resolved, but you may not want to hold your breath for the time being. The original story follows.