Debugging on Prod

The worst type of bug is one that only happens on prod. And only on prod. If you checked this blog in the past few weeks, you might have encountered a big fat 500 error. I'd had the same design for 10 years, and I wanted something fresh. But who can redesign without also improving the underlying code? I deleted a whole bunch of things: old templates that were never used, post.new7.old.php, a pile of unused CSS. I just had to. I deployed a first version and all the pages worked just fine. But then I got cocky. I decided to also improve the underlying code using GitHub Copilot. I was vigilant at first, reviewing every single line of generated code. None of it was complex really, just refactoring functions and the like. But along the way, I got lazy. I let the AI update deprecated functions on its own. The next time I deployed, the website returned a 500 error. When I checked the logs, nothing came back. No errors. I looked at running processes and noticed several PHP processes pinned at…