No update; client crashing for many players

I haven’t updated my game for several days, but in the past hour, a significant number of my players’ clients have started crashing in my game.

I got my first message about it 40 minutes ago. Most of the comments on the game are complaints about this issue. Hourly visits has spiked 180% above the last hour, and visit length has dropped from 30 to 20 minutes. Concurrent players has dropped from around 1,600 to 800 players in that time.

I went in and was able to get this to happen to me twice within three minutes of joining the game, but was unsuccessful after more than 6 minutes for two other attempts.

I currently have no idea on a repro. I’m looking into my code to see if I’m doing anything too intensive, but it doesn’t seem like there would be any problematic code, given that the game seems to have had almost no performance problems until now.