Answers sometimes become obsolete. New solutions arise that were not technically feasible at the time that the question was originally posed. People decide that the old way of doing things is no longer a good idea. This goes for answers on main sites as well as on meta sites.

In How to deal with obsolete answers?, several suggestions were raised, but I don't find them satisfactory.

  • Deleting is not appropriate, I think, since it removes all trace of the answer, and even obsolete information is sometimes useful. It leaves a void, and there is even a risk that the void could be filled by someone else writing a similarly obsolete answer. I also believe that is is inappropriate to strip the original poster of reputation points that were rightfully earned in the past.
  • Editing the answer to provide a new solution is an underhanded approach, since the practice of radically altering posts is prone to abuse. Who is to say that all the voters who upvoted the original answer agree with whatever new advice is added? It's even worse if someone other than the original author of the answer violates the author's intent. Editing also fails to confer reputation commensurate with the effort, if the new answer is completely different. Additionally, it might not be desirable to bump an old post onto the front page.
  • Downvoting To counteract all of the upvotes, you would have to rally a downvote brigade, which is neither realistic nor desirable. There's no need to hurt the original poster's reputation just because an answer is no longer relevant. Furthermore, all previous upvotes are locked in unless the post is edited, so the concerns raised above about editing also apply.
  • Commenting is insufficient, because it could be buried at the bottom of a long thread. Also, comments on Stack Exchange are designed to be of a somewhat transient nature. Comments also don't alter the order of presentation of answers.
  • Locking is currently possible only for a "Content dispute" or for "Offtopic [sic] comments". As the guidelines say, "posts should only be locked when something seriously bad is happening. A locked post cannot be changed in any way or voted on". I don't think that obsolete information qualifies as "seriously bad", or that editing/voting should be prevented.

I think a feature enhancement is called for!

  • 5
    Once this gets implemented, this would also be very useful on Stack Overflow. A workaround that was necessary 5 years ago isn't today's best practice. Obsolete notices wouldn't solve all problems, but would make it much easier to maintain high quality.
    – amon
    Commented Nov 25, 2014 at 18:51
  • 1
    1) How often does this occur? 2) Who decides that a post is now obsolete? Commented Nov 25, 2014 at 18:54
  • 1
    @MartijnPieters 1) I don't know how to gather frequency stats, but when you do encounter the issue, it's befuddling, for the reasons stated above. 2) In my proposal, any user can flag a post, ideally with supporting information (an link to documentation, a newer answer, or an existing comment). A moderator would have to make a decision based on the evidence. Commented Nov 25, 2014 at 19:12
  • 10
    Moderators are supposed to be able to moderate without domain knowledge. I'd argue that they are not the right people for making that decision because deciding whether something is obsolete requires domain knowledge.
    – Mysticial
    Commented Nov 25, 2014 at 19:22
  • @200_success I'd reject that out of hand. It should never be down to one user, and mods do not have the domain knowledge to judge the evidence. Commented Nov 25, 2014 at 19:27
  • 5
    Then make this a review queue... tag badge holders may review a post against brought evidence and "vote" on an answer. That way mods are out of the dilemma and posts can still be marked as obsolete. Commented Nov 25, 2014 at 21:43
  • 2
    @Mysticial and MartijnPieters By that logic, the legal system would fall apart because judges aren't domain experts in all the cases they rule on. If a moderator doesn't know the answer directly, he/she can do some quick research, look to see if a more up-to-date answer exists, seek guidance from the community, defer to another moderator, or even reject the flag for lack of clear evidence. Commented Nov 26, 2014 at 10:52
  • <s>What about a post notice?</s> Never mind; now I've seen (and voted on!) your answer.
    – MTL
    Commented Jan 7, 2015 at 17:12
  • @200_success why not use your OP binding dupe vote? ;) Commented Aug 2, 2015 at 16:07
  • @ᔕᖺᘎᕊ Because the iOS app doesn't offer it. Commented Aug 2, 2015 at 16:10
  • oh lol @200_success! didn't know :) Commented Aug 2, 2015 at 16:11

3 Answers 3


A moderator post notice could fit the bill nicely. Currently, there are three types of notices:

  1. citation needed

    This post does not cite any references or sources. Please help improve this post by adding citations to reliable sources. Unsourced material may be challenged and removed.

  2. current event

    Post is related to a rapidly changing event.

  3. insufficient explanation

    We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

I propose a fourth type:

  1. obsolete

    This post may contain obsolete information.

It would be nice if answers were ordered such that posts marked as obsolete were sorted as if they had a score of 0.

Some advantages of this approach include:

  • The notice would be more prominent than a comment.
  • Readers can draw their own conclusions as to what to do with the information.
  • Previously earned reputation is preserved.
  • Other answers can bubble up to the top.
  • This feature piggybacks on an existing feature (in fact, it complements the "current event" post notice).

The only drawback I can think of is that it places moderators in a position of having to judge whether to post the notice, but I don't think that it is significantly more burdensome than with the existing kinds of post notices.

  • 9
    This would be a great solution – under two conditions: (1) The notice should be displayed above the answer so that I don't have to read obsolete info. (2) There would have to be a new kind of “obsolete” flag so that users can request the mods to apply the notice.
    – amon
    Commented Nov 25, 2014 at 18:47
  • 2
    @amon: I don't see it becoming its own flag type, unless it's also incorporated for the other notices. But I also see this more useful for Meta, as moderators themselves don't need to decide themselves if any main site content (domain knowledge) has become obsolete.
    – Jamal
    Commented Nov 25, 2014 at 18:58
  • Question: what would this moderator notice do to accepted answers and the "credibility" of the checkmark? Should an answer marked obsolete be allowed the green tick? Commented Nov 25, 2014 at 20:50
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    @Vogel612'sShadow The mod notice should not strip off the acceptance checkmark. I think that the "obsolete" notice should override the sort order, though. Commented Nov 25, 2014 at 20:55
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    Since posts notices are managed entirely by moderators, this is requiring moderators to be evaluating the technical merit of the posts. They may not have the expertise to know if a given answer is or is not obsolete, and it's not like they can just take the word of a flagger. Mods applying the notice also doesn't scale; there's just too much content becoming obsolete for them to be able to manage it on their own.
    – Servy
    Commented Jan 7, 2015 at 17:48
  • 1
    @Servy Maybe we could allow this particular "mod notice" to gold badge holders, if (say) 5 of them agree that the answer is indeed obsolete. Commented Jan 8, 2015 at 9:25
  • @200_success it would be burdensome of the moderators of larger sites (like Stack Overflow, Server Fault, Super User, Gaming etc.) where the moderators can't be expected to have encyclopaedic knowledge of the site's topic.
    – ChrisF Mod
    Commented Jan 8, 2015 at 12:27

I think adding a new flag will be a good solution.

It will work like this:

  1. User finds a question or answer which is out-dated
  2. (S)He will flag the question or answer as outdated
  3. Moderator or high-reputation user will be able to see such flags
  4. Verification
  5. If obsolete then the question or answer is marked as obsolete

This must be coupled with the ability to search only for posts marked as obsolete which can then be updated with appropriate information.

  1. This will help the community to view specifically just questions/answers with obsolete mark and will enable quick update of information.

  2. People who are searching for answers to such questions will proceed with caution when using/applying answers flagged out of date

  3. This will definitely improve the quality of community wiki posts and facilitate preferential update of such posts which should be maintained up-to-date

This will work better if a higher amount of reputation is given when users update an obsolete post and it is accepted.

  • Thanks for correcting that grave error @Matthew Haugen
    – One Face
    Commented Jan 8, 2015 at 9:44
  • 1
    Why would a moderator be able to tell that an answer is outdated? We don't have encyclopaedic knowledge of everything on the site (especially not on a site like Stack Overflow, Server Fault or Super User) so there's no way we'd be able to validate the flag. It would have to be done by gold (and silver?) badge holders in the tags.
    – ChrisF Mod
    Commented Jan 8, 2015 at 12:17
  • Oops didn't think about that. I assumed that a moderator of a site would have general expertise in that site. I did not say tag because I don't know a way to specifically tag just one answer. I thought the only the question could be tagged
    – One Face
    Commented Jan 8, 2015 at 12:20
  • You can't tag an answer, so it would have to be based on the tags on the question.
    – ChrisF Mod
    Commented Jan 8, 2015 at 12:25
  • So if just one answer, let's say one way to solve the problem presented, is obsolete then the only way to intimate this with a tag would be to tag the whole question. That would increase the work load of people seeking to correct such posts. That's why I proposed a flag
    – One Face
    Commented Jan 8, 2015 at 12:27
  • Mods should definitely not be responsible for determining or even just verifying obsolescence. This must be voting-driven, somehow. OR do we put an auto banner on every post more than a year old, warning that it may not be applicable any more? A blunt instrument, sure, and not perfect, but.... Commented Mar 25, 2015 at 12:37

so-called "Out of date" answers aren't always bad answers.

Sometime people need information that you would consider to be "Out of date" This is especially true if the reason why the answer is "out of date" is because the technology changes.

Going by the technology changing example:

When new technologies come out, the old ones don't just evaporate and disappear. Normally, there are people who still use them, and they still need answers which apply to the old technologies.

You might be tempted to tell them to just update their technology, but it can cost a lot of money and/or time to update technologies, and sometime it actually makes financial sense to just not upgrade.

  • 5
    "When new technologies come out, the old ones don't just evaporate and disappear." Actually, some do. A removed feature of a web application, for instance, is no longer available to anybody. Commented Jan 7, 2015 at 17:06
  • 3
    Right; that's why the proposition isn't to delete the information, but rather to make a post notice about it.
    – MTL
    Commented Jan 7, 2015 at 17:15

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