I wanted to understand if Captcha, computer security codes to distinguish between humans and bots, often happen to me in this period when I have to add an answer on the site TeX.SE.

In the last week I had to run at least ten: buses, pedestrian crossings, traffic lights, bicycles, houses, shops. I am wondering if all this is specific to me, or a general occurrence.

  • 4
    I honestly cannot remember when i have seen a captcha. Are you logging in from some kind of internet café?
    – Johannes_B
    Commented Jan 8, 2019 at 17:16
  • 2
    I had to solve a few captures recently when I was writing a long answer here on Meta while I was having trouble with my internet connection.
    – moewe
    Commented Jan 8, 2019 at 17:16
  • @Johannes_B No, from my home. I do them all right, and I get more like mushrooms.
    – Sebastiano
    Commented Jan 8, 2019 at 17:18
  • It happens to me sometimes when I login from a new device or after having done a logout.
    – CarLaTeX
    Commented Jan 8, 2019 at 17:50
  • 2
    Avoid known triggers such as shared IP, for example in big companies, schools, universities, vpn connections, posting too fast (for example when composing the post in an external editor and c&p into tex.se), code only answers (?).... In praxis I find it also much faster to close the captcha and simply repost. Commented Jan 8, 2019 at 18:17
  • 3
    Captcha wants to find out if it deals with humans. How about marmots? ;-)
    – user121799
    Commented Jan 8, 2019 at 18:46
  • 1
    @marmot And ducks?
    – CarLaTeX
    Commented Jan 8, 2019 at 19:16
  • 1
    Marmots and ducks are protected species, like pandas. :) That's why there are no captcha species :-). I assume that marmots and ducks (I had one called "Tweety") have human features :-)
    – Sebastiano
    Commented Jan 8, 2019 at 20:39
  • I always get prompted for a captcha when I just copy&paste code into an answer. I usually cancel the posting, add one or two words to the answer and then post.
    – Skillmon
    Commented Jan 23, 2019 at 14:39
  • @Skillmon Excuse me very much. With a lot of sincerity I'm very tired for work reasons and I'm not mentally lucid. I ask you please if you can insert an answer so that you can better understand the actions that you have done with images. Thank you very much.
    – Sebastiano
    Commented Jan 23, 2019 at 18:27

2 Answers 2


In general I block third party scripts, so I never see the actual captcha, but only the SX internal message that I'll have to solve a captcha. This happens to me every time I try to add an answer that contains only code I just copied pre-indented from my VIM:

enter image description here

I then click outside of this banner and enter a few words to the beginning of my answer inside of the browser. After that I can post the answer without being prompted for a captcha again.

This is reproducible for me in 100% of cases.

  • For the time being, the problem has not arisen since the last answer I gave. If it should happen again, I will follow your instructions and add a comment if there are any problems. Thank you very much.
    – Sebastiano
    Commented Jan 23, 2019 at 18:37

The appearance of the CAPTCHA should be based on the The Complete Rate-Limiting Guide. I can see that the following scenarios might trigger it:

  • Seeing a question; writing up code that solves the problem; copy-and-paste the code only and posting as the answer and then working adding some mortar to your brick(s) to provide something more consumable.

    You want to be the first one posting an answer, so you want to post at least the code as soon as possible. Once you have something working, you post it, but fall prey to the "within 5 seconds of starting new post" CAPTCHA trigger.

  • Switching networks while being mobile and using the site to post content could trigger the CAPTCHA accidentally.

    A plausible scenario occurs that the system does not properly log your initiation of a post, triggering the CAPTCHA when you want to post, since it then thinks you may be within the "under 5 second limit" (see this discussion in the Tavern on Meta).

  • Being mobile may send multiple requests to SE that are similar, triggering the CAPTCHA.

The issue(s) around being mobile is difficult to replicate, since it's neither a code base problem (on SE's side) nor user error (on your side). It's probably just a small glitch in the network connectivity that isn't easily reproducible.

  • Dear Werner, everything you wrote exactly matches the request I made. Unfortunately, I can only put the green tick in one place, but for me both answers are to be checked in green.
    – Sebastiano
    Commented Jan 24, 2019 at 9:45

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