Is this a duplicate of bug 2585?

W wrote:

Bug 2585 is a bit long in the tooth and has already been implemented certainly for the (article) namespace and probably for all except category. Also the question of "no page but has members" is unique to categories. So I felt that a fresh discussion might help. Incidentally see http://en.wikipedia.org/wiki/User_talk:RHaworth/Archive_to_2011_Jan_14#Category:Wikipedia_sockpuppets_of_.E2.80.A6 which is where I got involved - one person fussing over being accused of sock-puppetry.

I remember MSIE has an option which decides whether a standard (included in MSIE distribution) page or the page sent together with HTTP 404 should be used when it meets HTTP 404.

Note, as it stands (in trunk), categories will return a 404 if the following 3 conditions are met:
*The category page doesn't exist
*There are currently no articles in the category
*There never was any articles in the category (or to be technical, there is no entry in the category table)

It would be trivial to make the check be the category page doesn't exist and there are currently no articles in the category, if we want to do that.

(In reply to comment #3)

I remember MSIE has an option which decides whether a standard (included in
MSIE distribution) page or the page sent together with HTTP 404 should be used
when it meets HTTP 404.

I believe that only happens if the body of the response is less than 512 bytes. Presumably most of our pages are above that threshold. In any case we already do this for articles, so I can't imagine its an issue

fixed in r80406

As a note. If you're editing a category (like any other page), you will get a 200 status code.