I recently encountered the following scenario:

  1. OP asks a question which is missing some information.
  2. Answerer asks for clarification in a comment.
  3. OP clarifies in a comment but does not edit the question.
  4. Answerer answers question based on clarification supplied in the comment.
  5. OP deletes comment and adds contradictory clarification to the question.
  6. More people answer the new version of the question.
  7. Result: multiple contradicting answers answering multiple contradicting revisions of the question.

The particular question where I encountered this is this one, where I am the Answerer in the above abstract scenario: Is using multiple UUIDs decrease chance of collisions exponentially? (In case you are wondering: in a comment, the OP had originally specified they wanted answers for version 5 UUIDs, then they deleted that comment and edited the question to specify version 4 UUIDs.)

How to handle such a question? In general, we advise askers to not change a question in such a way that existing answers are invalidated, and usually, the most appropriate response is to ask the OP to roll back the edit. However, in this case, the clarification was only provided in comments, and is now deleted, so technically speaking, the question was never changed. Or was it?

Also, I received no notification of the change, so I only discovered it two days later, at which point other answers have been supplied based on the new clarification, which would be invalidated by the rollback.

3 Answers 3


Before editing the question, I would probably edit the answer, and explain why it answers a slightly different question than the one which was asked (refering to the deleted comment and the edit). It is not unlikely that others, when trying to find information about related topics, find your answer still useful, even if it does not fit to the last version of the question literally.


This is a tough one.

One option would be to edit the question after getting the clarification in a comment. You can even use the edit description to note that the clarification edits were derived from a comment. If there's any dispute, mods can see deleted comments on a question and untangle the mess. If the comment/edit were wrong and there are good answers, then the asker can always ask a new question and link the two.

However, in the situation you describe, the best thing might just be to delete the non-matching answer and move on. It's the least work for everyone. If you want to preserve the answer, you can always write up a question and self-answer it. Wouldn't be too hard - you have the answer and you can use the original question as a basis. Linking the two in the body or as a comment would also link them in the Related Questions.

The lack of notifications is something that could be improved. But that's probably a Meta SE question.

  • Yeah, looking back, asking the OP to put the clarification in the question, or editing it in myself would have been the right call. Not that I care much about that particular question, it was just an interesting sequence of events that I had never really thought about until now. Sep 20, 2020 at 11:06

From my standpoint programming is so complicated and nuanced that we can't help but be a bit "discussion-y" even in our questions and answers. I've always found this a paradox with the aims of the site to try to establish some canonical knowledge base of questions and answers. It's not so easy to ask the right questions on the first try, let alone try to answer them perfectly on the first try. There's always going to be some back and forth that's required unless someone is asking a how-to question so repeatedly-asked and obvious where 10 or more people in the room can scream the identical answer.

I always felt like the flow of information here should be accepted as dynamic, not static, and back-and-forth, not one-way. The format and the demographics simply don't allow much more than that. We are talking to each other in our Qs&As, not one canonical Q leads to one canonical A. This is more like a chat than an e-mail. And I think a lot of the design of the site, to eliminate what might seem like chatty noise in between, cuts a lot of vital info... like in the case where someone answers a question that gets invalidated by such discussions (especially if they're deleted). The chattiness is going to be important in many cases. It's part of the signal, not the noise.

This site's aim to be both Q&A and knowledge base is a largely conflicting design requirement. We can't expect average Joe to ask a question and cement some canonical answer in stone that stands the test of all time. This site, by design, must be a lot more dynamic and chatty than the volunteer mods want it to be. If they want the canonical then it has to stand above the Q&A in its own section, not hope the average guy will ask the right question and the perfect person will answer it beautifully every single time. This is closer to a chat site than a true knowledge base no matter how much we wish it to be the latter. One only needs to open up the site and look at a random sample of Qs, and comments, to see what it really is, and most likely always will be. So of course with a chat site like this, focusing on Q&As, people are going to be confused if comments disappear that provided vital context for answers. This is a chatty site.

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