I clicked the arrow next to a comment, and to express my agreement with it. I accidentally clicked it again resulting in the following error message:

enter image description here

Which states:

You cannot mark a comment more than once

But as what did I mark this comment? Helpful, favorite, brilliant, stupid?

I think this message could use some clarification.

  • 9
    To those who might receive this question negatively: while the cause of the error message may be clear, the message itself is confusing. Jan 7, 2020 at 22:31
  • 5
    I can't reproduce that message. Clicking on the arrow triggers an upvote. Clicking again undoes it (after confirming a prompt). Clicking a third time shows a message saying you already retracted your upvote and can't vote again. Jan 7, 2020 at 22:49
  • 1
    @Kodos it happens if you navigate away and back using the browser forward / back buttons or if you vote from another browser window.
    – PeterJ
    Jan 8, 2020 at 0:38
  • @PeterJ thanks I repro'd. Seems like a bug? Jan 8, 2020 at 0:41
  • 1
    I think it'd be expensive to fix because the page is loading from the browser's cache in the initial state so it'd need a server call to update. But maybe when it goes off and finds you've already voted rather than a message it could just silently put the blue arrow on the comment, but I think just changing it from "mark" to "upvote" would make it a lot clearer.
    – PeterJ
    Jan 8, 2020 at 0:50
  • Yes, thinking back this indeed happened when I used my browsers navigation buttons. @PeterJ
    – Luuklag
    Jan 8, 2020 at 7:18

1 Answer 1


I was able to reproduce the issue by opening the same post in a new tab, upvoting a comment from the earlier tab, and attempting to upvote the same comment from the new tab.

While this message may seem like it can only be triggered if one tries to intentionally exploit it, it can also be triggered in certain accidental circumstances, e.g. if you navigate back to the page, your browser may have cached the prior version of the page that didn't show your upvote, and one might think "I remember upvoting this" and trying again, only to receive the error message.

At the very least, it should be made less confusing:

You cannot upvote a comment more than once

An alternative, possibly better solution would be to do the same thing that happens with post votes in this case: appear to upvote the comment and update the score, but do nothing on the backend.

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