[rufo]

I have a history of asking incredibly basic questions about the assumptions that are going in to a debugging issue for exactly these kinds of reasons. Something changed somewhere; so have we verified our basic assumptions that things are what we think they are... or did something change under our feet without our knowing? Or maybe we actually have a different understanding of the state of the world, and one of us is actually wrong?

It's not fruitful every time, but the number of times you skip asking those questions and chase something around, only to realize that, actually, it _was_ the ridiculous/simple thing... well, it feels a lot better to realize it earlier :)

(personal footnote: do be mindful of the context you're asking in! I feel like in general those sorts of questions are _fairly_ well tolerated by technical people. Sometimes you feel a bit stupid asking the question, but many of the systems I've worked on are large and complicated enough that it's not that weird - and if there's downtime and a healthy team, people genuinely want to hunt every possibility down. People not used to that, though, will sometimes bristle a bit, thinking you're implying that they're stupid and don't understand the basics. There can be ways to be more tactful, but at the very least, it's worth being aware of that reaction so you can follow up with a "just making sure I understand!" or something like that.)