As of today, if I try to edit any of my answers or questions on the main site in Firefox, MathJax renders very slowly and incorrectly in the preview.

Some lines (which look fine before I click "edit") won't render at all in the preview, and the lines that do render in the preview don't have proper spacing or alignment. And nothing renders at all until I type something.

I'm encountering similar issues when trying to compose a new answer.

The preview works correctly in Chrome.

I'm using Firefox on a Windows machine.

A clean install of Firefox didn't fix the issue.


The preview was working correctly in Firefox earlier today (12/29), but now it's broken again.

Second Update:

This is only an issue with the main site. The preview on Mathematics Meta works correctly in Firefox.

Third Update:

I found a way to get the preview to work most of the time, but it requires the use of a content blocker.

Refreshing the page alone doesn't help. But if I block the connection to cloudflare.com, refresh the page, and then allow the connection to cloudflare.com again, the preview then works most of the time.

  • $\begingroup$ Have you tried clearing your cache in the browser? $\endgroup$
    – hardmath
    Dec 26, 2023 at 5:30
  • $\begingroup$ @hardmath Yes. I also disabled all extensions and turned off tracking protection in Firefox. $\endgroup$ Dec 26, 2023 at 5:37
  • $\begingroup$ I tried opening an edit on a short post with MathJax in Firefox, but did not observe any difficulty in rendering. Perhaps you could link to a post which gives you slow preview, etc.? $\endgroup$
    – hardmath
    Dec 27, 2023 at 15:59
  • $\begingroup$ @hardmath It's not any posts in particular; it's every post, including other people's posts. It must be an issue on my end. $\endgroup$ Dec 28, 2023 at 4:46
  • 4
    $\begingroup$ "Me too!" I've experienced the issue intermittently over the past month or so. It's intermittent in the sense that it changes day-to-day, though generally not post-to-post. On days it's not working, it fails everywhere. This was observed on two separate Linux machines, so it seems unlikely to be a one-off "cache corruption" issue. Anyway, clearing the cache didn't help. Currently, I'm seeing it on Firefox 121.0.1; not sure what version was installed when I first noticed it. $\endgroup$
    – K. A. Buhr
    Jan 19 at 21:48
  • 1
    $\begingroup$ @K.A.Buhr If I'm just browsing the site, Firefox renders MathJax correctly and much, much faster than Chrome. In the past, MathJax issues were always fixed promptly, even minor issues. But now a MathJax issue will only get fixed if it's an issue that completely breaks MathJax rendering everywhere and on every platform. $\endgroup$ Feb 22 at 21:52
  • 1
    $\begingroup$ @hardmath Try this: mathoverflow.net/questions/461631 If it opens fast for you, then, indeed, it might be a local machine issue (which I occasionally experience too) but if it doesn't or opens with an unusual font, then there is a problem on the site. I had really hard time editing the posts there despite the fact that I pre-typed big blocks in a TeX editor and just used copy and paste most of the time. $\endgroup$
    – fedja
    Mar 7 at 1:45
  • $\begingroup$ @fedja: Thanks for following through. I don't see a delay now in browsing that MO post or opening it for editing (no unusual fonts). A few days ago there were SE network wide problems with unresponsive pages, but your observation seems much more specific. $\endgroup$
    – hardmath
    Mar 7 at 2:48

1 Answer 1


I use Opera, and with this web-browser, I duplicate the tab, since sometimes the math rendering gets stuck with bizarre errors. That usually fixes the problem. Also, consider www.stackprinter.com to view edits that are saved:

StackPrinter main screen

Although the site moderators usually discourage saving questions rapidly multiple times, because it bumps the question up in the list of displayed questions, for just one save, this might be a good troubleshooting step. I have not encountered issues with multiple saves of answers (which also suggests a troubleshooting route of does the issue occur just with answers or just with questions and vice-versa).

Stack Printer can be used to see questions and answers together well-formatted (usually) and has yielded excellent results for me. Especially when the rendering on the main Stack Exchange website is more suited to ask or answer questions rather than to print out the questions and answers for other reviewers to share and respond to, stackprinter sometimes makes it easier to print out the last version to edit and proceed.

Some additional simple troubleshooting steps that might help you:

  1. Below the question or answer, there is a preview section for the related output. It is important to click the mouse button on top of that preview section to have the text reload more quickly. I always do this clicking on the preview text on the bottom because the update is very much too slow without that.
  2. Do you have the latest version of your web-browser? Sometimes there are fixes that require the latest version. Also, using a freshly downloaded different browser resolves issues that are rooted in conflicts that are isolated with a dedicated browser to your Stack Exchange site.
  3. If you duplicate the tab, does the issue persist? Some issues are due to something stuck with a single tab that does not happen when the tab is duplicated.
  4. If you save the text of the answer or question in a text editor, and then you reset your web-browser, and paste from scratch, does the issue persist?
  5. Does saving the question or answer resolve the problem, after a browser reset (especially removing cache and turning off plugins)? There are some known issues where before saving the question or answer, that the formatting is less than ideal, but this is resolved with the save.
  6. If you paste the text into another Stack Exchange website, does the issue persist? Sometimes there are some subtle differences from site to site, which makes rendering work fine on one site but not on another.
  7. Do you have virus-protection software installed or else is your operating system otherwise secure against viruses? It is the "elephant in the room" that some operating systems and browsers are prone to viruses. Sometimes a simple un-install and removing all of data for the browser and reinstall helps. Sometimes a new user on a multi-user operating system resolves the issue with the same browser. Sometimes there is indeed a virus that has to be removed to solve the problem.
  8. Does the issue happen with another user (especially when the question or answer is saved). I cannot guarantee that I could see each of your issues, but I would definitely appreciate a comment link to me if it is available.

I am very interested about this issue since I have also encountered issues from time to time. So far, almost everything essential is resolved on my-side. But the topic is important as some bizarre formatting might pop up from time to time, and it is better to be prepared with an answer that with a question.

Thank you for your question post!


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