As far as I can tell all of the browsers in "Grade C" and most of the browsers in "Grade X" currently receive the same high quality math typography from Wikipedia that the "Grade A" browsers get. So if you are suggesting that it's completely fine if every reader who doesn't have "Grade A" browsers or current hardware should receive ugly or even illegible mathematical notation, that would be a huge downgrade/regression compared to current support.

The page https://en.wikipedia.beta.wmflabs.org/wiki/Extension:Math/Native_MathML/Reported_Cases has completely broken layout so that's not too encouraging. Also this just shows random snippets of formulas out of context, which is okay for testing certain specific features but doesn't do a good job of showing how mathematics appear in context in articles.

In my opinion the #1 requirement for any such potentially disruptive change is to set up a test environment with at least several dozen devices of various display size, operating system, browser, browser version (representing versions back maybe 10 years), and make a test page with a wide range of mathematical expressions drawn from wikipedia articles and shown with sufficient context so that they appear as they would in-article, and then get the rendering across devices evaluated by experts, with release blocked until there has been a sign off that rendering has consistently high quality. This would probably be easiest if a way were figured out to get screenshots of these automatically produced so they could be easily inspected remotely, rather than needing to bring someone to a physical place where the devices sit.

No you should most certainly not follow any plan like this. The native mathml mode remains completely unready for wide-scale production use, and switching to it as a default for any of the large language Wikipedias any time in 2025 is going to be a huge mess with lots of angry push-back from Wikipedians and Wikipedia readers. Many readers' browsers will render formulas in various broken ways, and most of the rest will have unacceptably ugly spacing and layout problems on many pages.

Math articles are still vaguely readable with this bug, but thousands of them have messed up formatting, in some cases pretty severe, and it's hard to get a good sense of what the appearance will be (once the bug is fixed) which slightly hampers editing in the mean time. If it takes two or three days to roll this back it's not the end of the world, but the faster the better.

In the mean time this can be worked around in two ways:

While we're at it, as you can see from Edtadros's screenshots above, the vertical alignment of inline math is also off, worse than it was yesterday.

I never noticed this ticket before, but please do not apply any change of this type. It will break the rendering of historical versions of every Wikipedia article with math in it. The "do nothing" alternative is far preferable.

Is today's regression where block math elements in desktop view are no longer rendering on a new line related to fixes for this? Many pages are currently experiencing this new rendering bug across Wikipedia.

Thanks for your quick work!

I'm running into the same issue. Couldn't edit (with a message about needing to log out), then couldn't log out ("invalid CSRF token"), cleared my browser's saved data to force log out, and now it's impossible to log in.

I'm currently running into this symptom, 30 March 2025. Any advice on what to try? I can't log out or make edits at the moment. When trying to log out it says I have an invalid CSRF token, and when trying to make edits it says I need to log out first.

Sorry: I missed this reply in 2023.

In every browser on my computer, looking at https://en.wikipedia.beta.wmflabs.org/wiki/Extension:Math/Native_MathML/Reported_Cases the MathML examples are entirely unacceptable. The MathJax SVG has some issues but mostly looks okay. It's plausible that the problems with the MathML rendering is just down to using bad/broken fonts with insufficient character support, bad glyph shapes, poor metrics/kerning, etc. It's never ever going to work to expect every Wikipedia reader to bring their own math font.

In response to the "plan" at the top of this page:

The above is what the MathML rollout page looks like in my browser. Leaving aside the math font being significantly too large in the top "SVG" example, as you can see, in the MathML version:

Even though Mediawiki generally uses space for paragraph breaks, the vertical spacing above and below math formulas should be the same irrespective of where they are relative to paragraphs, and ideally should be relatively little. Extra vertical space around block elements like formulas is not obvious enough a signal of a paragraph break, and having inconsistent spacing doesn't look intentional, it just looks like a sloppy bug.

@Jdlrobson The issue is the interaction between floating images and the CSS for display=block math formulas, as viewed in the desktop site. However semantically invalid it may be, the previous colon indentation method renders correctly (or at least correctly enough to be usable), whereas the display=block method renders (in my opinion) severely incorrectly.

Are those all visible now?

Here's a screenshot from English Wikipedia "Ellipse":

For whatever it's worth, this bug definitely is not caused by article content changes of the past 2 weeks. It affects some pages that have not been modified in that timeframe.

Is there a place where we can test a wide variety of formulas with the new rendering mode?

This bug makes <math display=block>...</math> fundamentally broken, and encourages authors to prefer using :<math>...</math> for indentation even though that generates a definition list which causes problems for some screen readers, or alternately to jump through hoops to instead adopt a template workaround.

In a related example, if you explicitly add the following (invalid as written) raw HTML to a wiki page:

Would it be possible to add some facility for wiki authors explicitly describe two versions of the formula for different sized displays?

I made a demonstration here, https://en.wikipedia.org/wiki/User:Jacobolus/math_block_example