It appears that the MO TeX does not understand macros \mod and \pmod any more; it used not to be the case. As a result for many questions the typesetting is broken.

  • $\begingroup$ Apparently, Dima is not the only one having a problem with pmod; mathoverflow.net/questions/37097/… $\endgroup$ Jan 3, 2016 at 14:59
  • $\begingroup$ On my Mac symbols \mod \pmod \pod are not displayed, as well as \binom and \choose. $\endgroup$ Jan 3, 2016 at 18:05
  • $\begingroup$ However \bmod does work. $\endgroup$ Jan 3, 2016 at 18:06
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    $\begingroup$ MathJax v2.6 was released on Dec 30. If clearing the browser cache helped, this error may have come from having components from different versions of MathJax in the browser cache simultaneously. $\endgroup$ Jan 10, 2016 at 2:11
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    $\begingroup$ @PeterKrautzberger Could you write an answer? When I had this problem and arrived at this page I did not notice this tip. I think a more prominent place would be better. $\endgroup$
    – Dirk
    Jan 25, 2016 at 13:32
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    $\begingroup$ @Dirk thanks for alerting me. I never got a confirmation and I'm not an active user. Will write one now. $\endgroup$ Jan 25, 2016 at 22:05

2 Answers 2


MathJax v2.6 was released on Dec 30, close to the OP. These updates can lead to errors if a browser cache contains a mix of MathJax components with different versions. In that case, clearing the browser cache from all things MathJax (and for some browsers, additionally restarting the browser) should help.


Seems OK to me...

$5 = 7 \pmod2$

$5 \equiv 7 \mod 2$

Perhaps Dima should tell us what OS and browser versions he is using.

  • $\begingroup$ Have you checked the main site as well (meta might behave differently)? $\endgroup$
    – Stefan Kohl Mod
    Jan 3, 2016 at 13:23
  • $\begingroup$ Now I did, and it looks the same as here. $\endgroup$ Jan 3, 2016 at 13:46
  • $\begingroup$ Firefox on Ubuntu Linux 14.04 $\endgroup$ Jan 3, 2016 at 14:57
  • $\begingroup$ works on my Android phone, though $\endgroup$ Jan 3, 2016 at 14:57
  • $\begingroup$ And now it is OK with the setup that did not work when I posted this question. (I can say that I had that \mod etc problem for a couple of days at least). $\endgroup$ Jan 3, 2016 at 15:14
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    $\begingroup$ Both of these render as "[Math Processing Error]" for me... $\endgroup$ Jan 3, 2016 at 20:05
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    $\begingroup$ @AndyPutman: Did you try clearing your cache? $\endgroup$ Jan 4, 2016 at 14:21
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    $\begingroup$ When I first visited this page, I saw errors as mentioned by Andy Putman. When I refreshed the page, the MathJax came out fine. $\endgroup$
    – JRN
    Jan 5, 2016 at 4:07

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