Say I have the question "How do I solve A". I do a search, and I find that Bob has already posted this exact question. He has also posted an answer, in which he says "I figured out I could avoid the issue by doing X", and marked correct.
However, I can't work around the problem. I need an actual solution to A. I can't post a new question, because then it will be immediately closed as a duplicate. But the old question is not going to get any more answers, because it already has an accepted one.
What am I supposed to do?