Answer I gave that was technically correct and completely useless

Someone asked me a technical question last month. I gave them an answer that was accurate, well reasoned, and did not help them at all.

I could tell because they thanked me politely and asked someone else.

What they needed was not the correct answer. It was the answer that fit their situation, which was messier than the one I had described. I had answered the question as written instead of the question behind it.

I have been on the other side of this too. Asked an expert something, got a perfect answer, and walked away feeling stupid because it clearly was not for me.

The hardest part of helping someone is figuring out what they actually need to hear, which is rarely the same as what they asked.

Have you ever given a correct answer that failed to help? And how do you get to the real question underneath?