I see nobody answers. I am closing the task by myself. If there is a problem, reopen it.

The discussion was moved to here.

No problem.

Thank you. I have posted an edit request at that page on en.wiki.

First of all, @Jonesey95, you can't do it only in vector or only in your account. We are talking about removing pages from category, so it can be done for your entire wiki and nothing else.
Second of all, there is no link for this case help, because it's too obvious.

1. Create a new page [[{{ns:8}}:math-tracking-category-error]] in your wiki.
2. Put there for example a code:

{{#switch:{{NAMESPACENUMBER}]|1|2|3|118|2600=:|Pages with math errors}]

3. Where the numbers list is all namespace numbers where you want just a message, not a category - here, for example, talk, user, user talk, draft and flow.
4. And the last parameter is the category name (you'll see it in the wiki editor in the page creation moment).
5. Save the page.
6. Open one page with a math error in good namespace for editing. Make sure the category is there.
7. Open one page with a math error in bad namespace for editing. Make sure the category is not there.
8. If there is a problem, replace ":" with "-" in the code and try again.
9. When you are sure it works, run a nulledit bot on the current category content.
10. Done.

I would love to do it myself (for everyone, not just in my own vector.js). @IKhitron, do you have a link to instructions on how to take care of it on en.wiki? Thanks.

I meant one line in wiki code, @SalixAlba and @Jonesey95, not jawascript.

It is a little annoying. But I'm convinced it is worth the extra effort. In time the number of false positives will go down and each page is re-rendered. Some talk pages which discuss rendering errors will remain.

But @Jonesey95, you can do it in a minute by yourself.

If possible, it might be a good idea to limit the namespaces to which this category applies. For an example, see the Citation Style 1 error messages and categories on en.wiki, e.g. "Category:Pages with archiveurl citation errors":

@Aklapper? Or maybe @Quiddity? Thanks.

It looks like this is fixed in T134872 by https://gerrit.wikimedia.org/r/292576 We can probably close this as a duplicate.

So we now seem to have [[Category:Pages with math errors]] on en wiki at least.

Hello, @Aklapper. It works. I think you need close this task as resolved.

T32795: "Show edit toolbar" preference is confusing related (was removed from task description)

Change 281285 abandoned by Jdlrobson:
Show moved lines in diff view using JavaScript/CSS

With today's deployment of cross-wiki notifications (now enabled by default on all wikis), I'm closing this as resolved.

I left a longer reply on T33070#2253518. I wouldn't say this is a blocker, it just means you won't be able to (conveniently) add fair-use tags to files uploaded with UploadWizard…

@matmarex Is this a blocker to forbid deployment on other wikis?

I guess the desired feature is included in the mhchem package T98306?

You can move stuff -

Change 281285 had a related patch set uploaded (by Jdlrobson):
Show moved lines in diff view using JavaScript/CSS

Can I expect a maintenance script for cleaning up old entries?