This, but present tense, is my favorite. “What happens when you try x?” If they haven’t tried it, they can say, “hmm, I don’t know. Let’s see.” If they have, they can say, “it errors out” or “it sorta works but...” or whatever. In my experience it comes across as curiosity rather than judgement.
This is the other side of a bad coin: "why didn't you" assumes they didn't. Just asking if they did will automatically include asking why they didn't and what went wrong when they did, whatever the case may be, and without the tone of either of those.
This, but present tense, is my favorite. “What happens when you try x?” If they haven’t tried it, they can say, “hmm, I don’t know. Let’s see.” If they have, they can say, “it errors out” or “it sorta works but...” or whatever. In my experience it comes across as curiosity rather than judgement.
This is the other side of a bad coin: "why didn't you" assumes they didn't. Just asking if they did will automatically include asking why they didn't and what went wrong when they did, whatever the case may be, and without the tone of either of those.