Update: Bungie says Destiny 2 is now "slowly being brought back online," so while you may encounter a login queue, you should able to log in at the time of writing. It seems connection-related issues are still being resolved, so login errors aren't uncommon either.
Why are Destiny 2 servers down? Bungie pulled the game offline for emergency maintenance shortly after the launch of the Season of the Splicer.
The Bungie Help Twitter account confirmed that Destiny 2 would be down for emergency maintenance at 12:30 PST / 3:30 EST / 8:30 BST, but didn't give a timeframe for the maintenance. Bungie also acknowledged a sharp rise in error codes labeled Chicken and Honeydew, which were blocking many players from entering the game to begin with, or properly playing the game if they managed to get in.
This is business as usual for online games and Destiny 2's seasonal rollouts. The sharp influx of players and new content routinely causes some day-one downtime for new seasons, but it's typically resolved fairly quickly. Community managers dmg04 and Cozmo reiterated that the live team is working on targeted errors as well as general stability. With any luck – and by luck, I mean a lot of expedited troubleshooting by the Bungie folks no-doubt scrambling while working from home – we'll all be splicing it up within a few hours at most.
We'll update this story as Destiny 2 is brought back online and the new season stabilizes. In the meantime, you can always gush over the dozens of new weapons we'll be chasing in the months ahead, not to mention the Fallen baby plushies that are coming soon.
The Destiny 2 Season of the Splicer trailer sets up a huge narrative shift that we can't wait to dig into.