This question was created on Server Fault, answered on Server Fault, I upvoted some of those answers on Server Fault, and then moved by consensus to Super User.

Now that the question is on Super User, I can upvote the same answers I previously upvoted on Server Fault.

  • 32
    I enjoy this bug, and would prefer it not be fixed.
    – Shog9
    Commented Sep 4, 2009 at 16:49
  • Note: I just noticed this is the case for comment upvotes, too.
    – dim
    Commented Apr 13, 2017 at 14:15
  • The same also applies to questions. The revision history is also nuked in the process, but I suppose that's a separate issue Commented Aug 8, 2019 at 12:03
  • @Olivia I disagree with the way this works (and could propose a comprehensive way of how I think it should work), but I guess it's not something that's really open for discussion at this point. Commented Aug 8, 2019 at 21:27

6 Answers 6


I was about to naïvely propose that they check with linked accounts before casting a vote, and suddenly I got a case of programmitis managerial and foresaw the things that would need to be done for that to happen.

Programming is hard, lets go eat waffles instead...


I just encountered this. I upvoted a question on Stack Overflow and then flagged it for migration to Super User, where I was there able to upvote it again. It's fun and all, but it seems like when the question is migrated, it should migrate my vote too, since I have an account on Super User. Not fair to those who don't link their accounts, I guess.


After the lecture of the answers from this thread and the Database schema documentation for the public data dump and SEDE I'm quite sure, answering your question literally:

It's because the Score fields from Posts table is copied, but the relevant entries in Votes table are not.

Answering implicit question:

While denormalization made that bug possible, it would be injust to say it's the denormalization's fault.

Yeah, copying Votes entries may be hard, if some user doesn't have account on the target site, but still there are other users who have, and nobody forced SE team to have non-centralized database of users, while login methods are centralized...

Just consider it a bonus for users able enough to write off-topic question that will be upvoted (instead of downvoted) before migration. Of course, it's not intended, it's not a feature, but it's not a bug because it won't be fixed within next 6-8 years.


I arrived at this question when a question I answered got migrated, prompting curiosity about the possibility of double-voting.

The answers, including Oded's answer to a duplicate question, say that it is an accepted anomaly:

This is a known issue, but for such an edge case, we are OK living with it.

One issue which hasn't been addressed as yet1 is that people can sign up to different communities with different credentials. This is different from creating sock puppets on a single site (perhaps we could call them gloves - things you wear to handle different situations). It might be troublesome to maintain multiple gloves, but no one's going to stop them from doing so.

Going to the nth degree to preserve one vote per user would mean that the programmers must address the issue of identifying gloves. I'd expect that gloves require some human input to identify - and then, only imperfectly. If two users on different communities were incorrectly identified as gloves of each other, the downside would be that one of them might be prevented from exercising their vote. To those for whom votes matter at all, that's probably untenable on Stack Exchange.

1 Except possibly the waffles fan perbert as part of his wide-ranging "things that would need to be done".

  • So, to clarify, you're talking about someone upvoting their own post by having an account on a site that it happens to get migrated to?
    – Catija
    Commented Jul 30, 2018 at 2:50
  • @Catija No, no - that didn't even occur to me. I was referring to someone having gloves on both the source and destination communities of a migration. They could have voted for someone else (up or down) pre-migration, and then vote again post-migration - even if programming was changed to prevent double-voting by one credential used across both communities. Voting for themselves would go against the intent of the Stack Exchange rep system regardless of whether they used socks, gloves or some other mechanism.
    – Lawrence
    Commented Jul 30, 2018 at 2:54
  • @Catija Thinking about your question a bit more - people voting for themselves would need both accounts live to profit from it. That reduces it to actionable sock puppetry. Gloves, on the other hand :) , relate to only one live account on each community - just not the same account in each case.
    – Lawrence
    Commented Jul 30, 2018 at 6:01

This is not a bug in the least. Votes on one site are not the same as votes on another site.

  • 15
    Then why are votes from one site migrated to the other with the question?
    – Alex J
    Commented Sep 4, 2009 at 15:24
  • 1
    I already answered this over on Jeff's answer when you made the exact same comment.
    – TheTXI
    Commented Sep 4, 2009 at 15:25

How is this a bug? You're voting on a completely different website. There is no cross-site voting "protection".

  • 69
    Then why are upvotes from one site migrated to another? By that logic, all answers should be moved with 0 status.
    – Alex J
    Commented Sep 4, 2009 at 15:22
  • 2
    does the user lose the rep from SO when it's transfered from the site? Commented Sep 4, 2009 at 15:22
  • 6
    All upvotes are moved over to keep the integrity of the rankings, such as on all of our FAQ posts. We had the problem early on that by clearing out all votes it woudl cause the best posts (which at the time were in the +100's) to get jumbled up with all the other garbage posts.
    – TheTXI
    Commented Sep 4, 2009 at 15:23
  • 1
    @Nathan: I believe that when a rep recalc is done, the user would lose any rep on SO after it was migrated away, because their answers are effectively deleted during the migration process.
    – TheTXI
    Commented Sep 4, 2009 at 15:24
  • 21
    But "bydesign"? Really? I understand that such protection might be hard, but surely there isn't intent there, at least when you have linked accounts. Commented Sep 4, 2009 at 15:32
  • 2
    ok, I could see this as a bug if the rep was counted twice. However, if no rep is gained on the original site, then I agree, that this is not a bug (just giving my blessing to Jeff's decision ;-) Commented Sep 4, 2009 at 15:33
  • 3
    If the original points are lost on the original site, it would still mean that the person loses one point on the original site, but is gaining two points on the other. That's one more point than it should be. Unless the migrated points don't count towards a user's rep, in which case disregard me.
    – Alex J
    Commented Sep 4, 2009 at 15:39
  • 6
    Jeff, the point is not to have "cross-site voting protection", the point is that if I have an account on superuser and I voted on a question migrated from stackoverflow, my vote should be migrated along with the question. It's a fun bug, but a bug nonetheless. ;-)
    – mpontillo
    Commented Feb 14, 2011 at 2:46
  • 6
    The problem with moving votes on migration instead of resetting everything to zero is that a migration from a large site to a small site can completely distort things on the new site -- if a score of 10 is high on a small site and then something comes in already at 30 from a site where that's no big deal, it looks like that's a top post on the new site -- but it's not, and that community wouldn't vote it up that high. Commented Apr 17, 2014 at 13:45
  • 10
    So if I go register to vote in another state and thus vote for President twice, it's ok, because it's another state, right? How is that illegal?
    – animuson StaffMod
    Commented Apr 18, 2014 at 23:35
  • 1
    The reason why this is a bug is simple: Q&As are migrated because they are off-topic at the originating site. Keeping those votes sends the wrong signal - remember how "gamification" works? This bug/glitch allows double-voting (aka cheating) which rewards users for off-topic posts... with all the moderation problems that come with that. Honestly, I'm left wondering why this hasn't been resolved yet, as a bugfix can be done quick and easy as I've described in my related Crypto.SE meta Q
    – e-sushi
    Commented Dec 3, 2016 at 18:43
  • I think, the votes should be moved, but on a way, that the vote of the users not having an account on the target site, should be invalidated. If a user registers on the target site, the votes of his migrated posts should be activated again. Furthermore, a migration event should also cause a possibility to change a vote (just as an edit). Maybe you could unite the databases of the sites to make these things easier to develop. It would also open the door before currently rejected improvements (for example, questions existing coincidentally on multiple sites).
    – peterh
    Commented Aug 11, 2017 at 21:11
  • @animuson I don't know how this is handled elsewhere but if you are registered in two EU countries you are not allowed to vote twice for at the EU elections. So in the EU it is illegal.
    – machine
    Commented Aug 19, 2019 at 10:49

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