In general, just placing a bounty won't help much, since the amount of comments and the pinned answer will make it difficult for most readers to get into the "good" one. I think we have to do some social engineering first, in order to have this new answer "shine" better.
There are many options:
- If the OP is still active, warn them about the accepted answer not being correct and suggest to unaccept it and suggest another one. (In this specific case, it seems to be the case... more or less, since the OP accessed the site few days ago).
- If the author of the accepted answer is still active, warn them about their answer not being correct and pointing how to improve it.
Leave constructive comments on what is wrong and what should be improved.
If the author of the accepted answer is no longer active and the question has quite a lof of views, votes... you can consider editing much of the answer (rewriting it) to make it correct.
You have to upvote correct answers and downvote incorrect answers.
Since an accepted answer gets pinned to the top, it is quite difficult to defeat the effect with another good answer: people won't probably see the new one. For this, I also find it important to write comments to the new readers. In bold, you can specify what is wrong and address readers to another one.
Since there are already many comments, you can flag them for removal, so their space is taken by new, juicy information. (Note: for the example question, I already deleted some that were obsolete.)
Post a new answer that addresses the question, with the aim of making it a really good answer, or place a bounty to challenge others to do so. Once you have it, that answer will be the one to mention in the comments to the question and accepted answer, saying: Hey, new users, check that other answer: it is the good one.
Make a new question with a correct answer that's accepted, despite in effect falling afoul of the duplicate question issue?
This seems to me to be somewhat of a last resort approach, but I think it would be a very good one: a curated question that can be expressly designed to be canonical. This way, you will be able to write it from scratch and focus in the examples you find that are relevant and useful. After it is posted I would find it normal and natural to make the original one as duplicate of the other: all in all, we want the best questions and answers to stand out. Also, if the original question has some good, unaccepted answers, you can ask to have a merge of the questions so they will all be in the same question thread and the former accepted answer will no longer be and will gently go down in the list of answers.