Obligatory: This is not a duplicate of this question, which is concerning the much older duplicate closure process.

Have a gander at this closed question. Notice anything weird?

The Community♦ user was invoked by the question asker to self-close as a duplicate (presumably of the comment below, which links to my bug report here), but the list of duplicates is entirely empty. So it would seem the question asker was able to close their own question as a duplicate of... nothing?

Screenshot, in case the post is altered later:

Any idea what happened here?

  • 7
    I believe it's yet another bug with having unanswered questions as duplicate targets. I've often seen site developers ignore this possibility and fail to test for it (since on main sites, it's extremely rare), and often bugs crop up as a result. Commented Mar 19, 2020 at 19:40
  • 1
    The closure also didn't delete the auto-comment. Unless it was edited.
    – Alex
    Commented Mar 19, 2020 at 21:54
  • 4
    Also can't fix it by editing dupe list (hammer privilege), the page is not found Commented Mar 20, 2020 at 9:48
  • As a temporary fix: Questions closed as duplicates but not telling the duplicate should probably just be reopened. Commented Mar 20, 2020 at 11:56
  • 1
    Should this question have status-review? Commented Mar 20, 2020 at 11:56
  • @Trilarion Considering this seems to be a one-off and there are no easy steps to repro, I'm not sure it needs elevation.
    – Spevacus
    Commented Mar 20, 2020 at 12:09
  • 2
    It’s not a one-off (any more): question link; images: question, revision history, timeline.  A possible common factor: in both cases the question was finally closed by Community♦; i.e., the OP voted to close. Commented Mar 31, 2020 at 4:34
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    @Spevacus Not a one-off any more. Commented Mar 31, 2020 at 15:20
  • 1
    @MarkKirby no, that's an old-style duplicate from ten years ago, when duplicate links were edited directly into the question body. This is about a bug that cropped up after the creation of the out-of-band duplicate link system, in which the duplicate link was stored separately as part of the closure details. Commented Mar 31, 2020 at 16:06
  • 1
    @RobertColumbia Fair enough, I deleted the comment.
    – Mark Kirby
    Commented Mar 31, 2020 at 16:10
  • 1
    Same here: math.stackexchange.com/questions/3603281/….
    – Martin R
    Commented Mar 31, 2020 at 17:12
  • 1
    It's happened again: meta.stackexchange.com/q/345876/336163 Commented Apr 1, 2020 at 17:15
  • 1
    @RobertColumbia I watched that one happen in real time.
    – Spevacus
    Commented Apr 1, 2020 at 17:16
  • 3
    I know that it is happening. My fix/logging isn't up yet. Thanks for your patience. Commented Apr 1, 2020 at 18:19
  • 1

4 Answers 4


2nd Update:

I have just run a backfill to fix all occurrences of this across all sites on the network (332 instances of it happening on the entire network that needed to be fixed, including 216 on SO). So if this appears for any questions closed after 2020-04-06T14:08Z then it means that the issues is still happening.

Issue with the edit/original screen for mods and gold tag users has also been fixed.

This issue has hopefully been fully addressed, the fix is on all network sites.

The issue itself had to do with cases where either the poster or the user who raised the close flag had low enough rep that they could not yet access the review queue, and thus the system marked their flag as a RecommendedClose. This led to weird scenarios in which the closing mechanism would accept the self-close action of the poster (following the recommendations for duplicate posts given in the post notice), but the system failed to record the actual OriginalDuplicateQuestionId value for the post (leading to the empty list).

Thanks to Adam Lear as well for help with this. We are pretty sure that we have identified the root issues here, and have added unit tests as well to verify the fix. I have also added logging here that will record more details in any cases where this will happen again moving forward. If you see any (with question closed after this update), please report them in a comment.

There is no easy way to retroactively fix all posts affected by this. However, mods and gold-tag users should be able to use the Edit function given at the top of the duplicate post notice to add back the missing duplicate question (without having to reopen and close). If you're not a moderator or gold-badge user, or you are a gold-badge user but can't find the right target in the post's comments, flag the post for moderator attention with a clear note about this bug and a link to this post; a moderator will fix it.

Thanks everyone for your patience with this and for your help reporting instances where this occurred.

  • May be this could aid in troubleshooting: in this example, though the dupe link is missing from the "Closed" message, it still shows under the Linked category in the right-hand side nav. It appears that the link to the dupe is not lost, it's just not showing.
    – mustaccio
    Commented Apr 1, 2020 at 18:32
  • Is there an effective way to manually fix this until the bug is fixed? I suppose moderators can reopen and close as duplicate, but that would only work for questions that are duplicated to one question (as far as I know - I don't see a way to add duplicates after closure). Commented Apr 2, 2020 at 8:55
  • superuser.com/questions/1538154/… another datapoint if it helps ;) Commented Apr 2, 2020 at 13:41
  • Can this please fixed asap. It defeats the whole duplicate system at the SE sites. Commented Apr 2, 2020 at 15:25
  • There are several questions exhibiting this bug on SESE - it has led to a question on our Meta as well as flags for moderator attention. I linked the Meta question back to this one, but further guidance on if there are manual resolutions or what we should do would be great. Should we do nothing and wait for the fix to be applied? Or should mods be reopening and closing to establish the links? Commented Apr 2, 2020 at 16:43
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    @JourneymanGeek Workaround posted to our mod room. Commented Apr 2, 2020 at 21:24
  • 1
    April 5th/6th, still happening. bicycles.stackexchange.com/questions/67043 I also note that the "edit" link to bicycles.stackexchange.com/questions/originals/67043/edit returns the classic "something bad happened"
    – Criggie
    Commented Apr 5, 2020 at 21:09
  • 1
    [...] should be able to use the Edit function given at the top of the duplicate post notice to add back the missing duplicate question Trying to use the Edit link leads to a 500 server error; issue seen on stackoverflow.com/questions/40323500/…. I reopened then closed instead. Commented Apr 5, 2020 at 23:10
  • 2
    @Criggie The post on bicycles was closed as duplicate at 13:38 UTC on Sunday and the fix hit prod at 14:50, so it predates the (hopeful) fix. Fixing the error with the Edit link now Commented Apr 6, 2020 at 8:08
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    @ShadowWizardisEarForYou understood, fix is on the way for that Commented Apr 6, 2020 at 8:42
  • 2
    Update: backfill has been run to fix this everywhere, and the error on /questions/originals/{postId}/edit for mods and gold-tag users for questions with no duplicates has also been fixed. Commented Apr 6, 2020 at 14:10
  • 1
    The bug is still appearing here :-( Is it possible that duplicates closed pre-2012 (when the "possible duplicate" link was automatically edited into the question text instead of appearing as a banner) are all now broken? Same problem here and here and here for example. (I just searched for old dupes.) Commented Apr 7, 2020 at 5:31
  • 1
    @rand those all look in order to me. The fix I put in should not (and does not appear to) have affected those old ones. Commented Apr 7, 2020 at 5:58
  • 2
    @Yaakov This is intended? :-( It's confusing enough that people are already raising mod flag(s) over it. There's essentially two duplicate banners, one of them empty/buggy and one of them manually edited into the question. If someone went and edited out the manual one, I believe we'd see exactly the same bug with the empty duplicate list. Commented Apr 7, 2020 at 7:31
  • 1
    @rand this is the solution in place for the old ones, predating duplicate notices, from when the duplicate text was put directly into the question. Went into this in depth several times on post notices post. Not ideal, but don't have better solution. And completely unrelated to this issue. Commented Apr 7, 2020 at 7:55


This has recurred in this question from today (now deleted by its author). I posted a question asking about it, which I let Community close as a duplicate of this one, and now my new question exhibits the same issue!

This is clearly an ongoing bug.


It seems to me as though we have (had) the same issue on U&L at How to disambiguate when grabbing filename by the middle and there are several matches?

I have since reopened the question after reading this post, but hopefully there's enough logging that this additional datapoint helps somehow.

  • 2
    Do non-logged user still get redirected to the dupe-target, even if there's a display bug for logged-in users? If so, IMO the better course of action is redundancy for the time being: close as dupe, leave a comment pointing to the dupe, but don't leave the thing open, which increases the risks of scattered information (which dupes aim to avoid).
    – Jenayah
    Commented Apr 4, 2020 at 12:59

We still have this bug, strong agree it is poor for new users who are most likely to post duplicate questions in the first place

enter image description here

  • 3
    This was closed as duplicate at 13:38 UTC on Sunday and the fix hit prod at 14:50 Commented Apr 6, 2020 at 8:06

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