@jscherber – that’s not quite what happened, but it’s a good guess.
When I very first uploaded the new version of the plugin, it was simply missing the updater file. There was a very brief window (about 15 minutes) when that file was missing, so only a few people who updated during that brief window are going to run into this problem.
I was careful to make sure that auto-updates would not completely break your site. If your plugin was updated automatically, then your master schedule might look funky for a little while until you run the database update, but the site will continue to function correctly. You can still access the dashboard without doing the database update.
So don’t turn off auto-updates! They’re still a good idea, and if I hadn’t goofed and left out that file for a few minutes, everything would have worked smoothly for you.