Some questions are getting closed as duplicates - good, the system is working. Unfortunately, some are getting closed as duplicates of other questions which are already deleted. This leaves all 1-9,999 reputation users left scratching their heads when they try to view the duplicate. Even worse, imagine being the author of the question and having your question closed as a duplicate when the original question isn't accessible.

I think something is wrong. Today I undeleted a question (left it closed) since it was referenced in the close-reason for another question. Comments indicated that people were clearly irritated that they could not access the duplicate

[Comment] Ok, who thought it was a good idea to close this as duplicate of a deleted question, which most people cannot even see? For the record, I'm reopening - clearly there's enough interest in this question. – Kobi 14 hours ago
[Comment] The PosibleDuplicate link is broken. Voting to reopen. – Rahul G 7 hours ago
[Flag] Closed as duplicate of a deleted question, fail. Thanks for moderating. – {username removed} 14 hours ago

My undelete-action was short-lived, as a few users returned to delete the post again.

It certainly cannot be desirable to reference posts that the vast majority of users cannot even see, especially when the author of the redundant question cannot see (at the time of writing this, the author has a reputation of 18).

I'm not sure what the solution is to this, but I'd like to hear some ideas.


Question: Why can’t there be an “ultimate” programming language?
Duplicate of: Why can’t we have a single programming Language?

  • I was surprised that the UI actually seems to allow me to do this - I noticed someone claiming question 16733547 was a duplicate of 16731788 although the latter had been since deleted - I only knew because it shows as deleted on the close dialog.
    – Neil
    Commented May 24, 2013 at 12:53
  • 3
    Meanwhile, as a regular user, I am frustrated because Google leads me to question 456, which was marked as a duplicate of question 123 which has since been deleted. Assuming that all deletions are legitimate, I am forced to support the notion of cascade deleting duplicates when you delete a question. That would solve the google issue I described, right? (I'm sure the answer exists somewhere else, today I'd rather have gone there first.) Probably the user should be queried: "are you sure you want to delete N dupes, too?".
    – daveloyall
    Commented Aug 8, 2013 at 19:35
  • I think that this should be on Software Engineering. Correct me if I'm wrong.
    – Cole Tobin
    Commented Sep 11, 2013 at 14:34
  • Just ran into this: stackoverflow.com/questions/9667264/gui-tool-for-postgresql
    – rogerdpack
    Commented Oct 18, 2013 at 17:19
  • Ran into this in CVQ, question needed closing but there were already 3 votes to close as duplicate of a deleted question :S
    – OGHaza
    Commented Mar 10, 2014 at 13:01
  • I suggest that questions closed as a duplicate of a deleted question automatically enter the reopen review queue when the other question is deleted. If the result is that the duplicate should stay closed, it should also get deleted automatically. Alternatively, duplicates of deleted questions can enter the low quality posts review queue and get automatically reopened if the result is Looks OK. Commented Feb 21, 2017 at 19:04

5 Answers 5


If the question is a duplicate of a deleted question, then it should be deleted as well!

I suppose I should explain my rationale for this...

There are certain questions which don't really belong on SO that get asked repeatedly: "Why isn't [some obscure language that I just got infatuated with] more popular?", "When will [some product I'm anticipating] be released?", "What's your favorite [something]?", etc. Like all duplicates, they should be closed once identified as such. And like all off-topic questions, they should be removed once closed.

Now, you could merge them with the original and thereby keep all the deleted answers together... but why bother when they're deleted!

That said... In this case, the second question ended up being more popular than the original, and was forced into CW (as is traditional for this sort of popular off-topic discussion question). So it'll probably stick around... Because, we hate fun.

  • 1
    Assuming the original was deleted justifiably. That may be the case, but there's still a transitional period between the close, and the ability to delete that OP's should be able to review the deleted original as well.
    – Sampson
    Commented Mar 23, 2010 at 22:30
  • 4
    Hey, I voted to close it before I voted to delete the duplicate. It's a shame that it took longer to collect the rest of the close votes than it did to collect the rest of the delete votes... But then, slow closing of subjective pap isn't a new problem.
    – Shog9
    Commented Mar 23, 2010 at 22:34
  • Problem: there are discussions that are reborn ever once in a time, especially on meta sites. Ideally, there should be only one "root original question" that is the dupe link for all the dupes. Often, this isn't the case, and so, broken chains can happen even if the original question has to stay (maybe it is not a bad question, but some of the dupes where deleted just because it keeps begin asked a lot). How can the link be fixed to point to the "official original question" in this case? Commented Jun 30, 2016 at 13:50
  • (see this question as a sample, how can we remove the dead dupe link? Just delete the whole question?) Commented Jun 30, 2016 at 13:52
  • In that particular case, click edit @SPArchaeologist.
    – Shog9
    Commented Jun 30, 2016 at 14:34

This isn't always easy to prevent -- consider this timeline:

  1. question A is posted.
  2. question B is posted.
  3. question B is closed as a dupe of A.
  4. question A is deleted for some reason that isn't relevant to explore.
  5. now question B points to an invisible question.

The only way to fix this is by some batch process in the back end that will search for "dangling references" and resolve the graph of dependencies. A dupe should always point to an open and undeleted question; if there is a circular dependency or there is no open/undeleted question to point to, a moderator should step in and merge or undelete (or delete!) questions as needed.

  • 8
    OTOH, step 4 could have a dependency check that requires removal of all questions that are duplicated to the question you want to delete, before it is deleted. Commented Apr 5, 2013 at 17:33
  • @ScottMcIntyre the dependency check is now in place, at least for questions using the newer duplicate system. I can't tell for the old duplicate system, where the post has a user-editable insertion of the duplicate link.
    – Cœur
    Commented May 2, 2018 at 10:06

I'm with Shog9 on this: if the original was properly deleted then the duplicated should be as well.

But I have developed a subjective impression that the ease of collecting the requisite close votes depends the category of close that is suggested. My impression of the order is roughly (from easiest to hardest):

  1. duplicate (easy as cake (well, waffles))
  2. belongs-on-* (usually easy)
  3. off topic|too localized|not real
  4. subjective and argumentative (sometimes very hard, indeed)

So I suspect what you're seeing is people trying to short cut one of the harder to get closes.

My recommendation: Close with the proper reason, but write a comment along the lines of "We deleted the same topic here: <link> for <reason>."

  • 1
    We should not be left with a dangling reference. On more than one occasion, I found a question [closed] as a dupe. I follow the chain of closures all the way to the point of eventually finding...nothing. Referencing a deleted post through a comment provides no more closure to finding the answer to a question I happened to be interested in than dropping into the hyperlink void. This doesn't mean that all closed questions have meaningful answers, but the one I was tracking down had something interesting about it or I wouldn't have gone to the trouble to follow the bread crumbs.
    – IAbstract
    Commented Mar 24, 2010 at 1:54
  • @dboarman: Referencing the deleted question isn't meant to provide an answer, it is an explanation that this fight has already been fought and the topic was found wanting. The alternative is that we have to fight it over and over again without any end in sight. If you don't think the original should have been banished, you should address you concerns to that issue (and yes, I understand that this is hard if you have less than 10k rep). Commented Mar 24, 2010 at 2:31

Couldn't this be solved in a way if there where question backtracks from OQ to dupes?

I mean, a question is marked as duplicate, and the original question will now have a small link list above of bellow the Related Questions pointing to the dupes.

This way, when deleting this question a small pop-up could appear pointing to the dupes, which would already have a relation and be denormalized into the question, without further stressing the server by fetching the possible dupes at closing time.


Following on from @Ether's use case, in my opinion when

  1. question A is posted.
  2. question B is posted.
  3. question B is closed as a dupe of A.
  4. question A is deleted for some reason that isn't relevant to explore.
  5. now question B points to an invisible question.


  • question B should no longer be marked as a duplicate

This is what seems to have happened already with the question the OP refers to.

Or, at the very least, the text could read something like

Possible Duplicates:

question (deleted)

rather than just

Possible Duplicates:


I came across this issue recently as I am trying to learn F#, and searched on google for "best online f# resources". Hurrah I thought as I saw that the 4th result was on stackoverflow: F# learning resources or tutorials. However the duplicated post has been deleted (and in fact only 1 out of the 4 links in the question and its comments works).

This experience wasn't upto the usual good experience I have on stackoverflow, and the moderators aren't able to address it. Removing the duplicate flag on questions that are no longer duplicated seems like an idea worth considering as at least it would stop the frustration of readers being officially directed to click through to a "Page not found". (Ideally if the duplicated post were undeleted, then the duplicate flag would be restored.)

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