Ugh, I made such a stupid mistake with Rails.
When I was creating my program, I had it set to use the development environment. I made sure everything was working. Then, I flipped it to production kind of rushed and I didn’t check that everything was working. Turns out, one of the tables was messed up. Oops. So, everything was working well for a while, and then, poof, it was broked.
I guess there are two lessons: 1) Make sure everything is working correctly AFTER you change to a new environment. That includes deploying to a new server. 2) Learn about testing so that I can catch these problems earlier.