Hi there, technical writer on the MDN team here. I noticed some of the pages are using URLs to MDN with an older scheme:
<h1 class="error-message">ERROR<br><a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/$1" target="_blank"><i class="vm vm-question"></i></a></h1>
I presume this is to link to status code reference pages when the visitor sees one. The new scheme is: HTTP response status codes - HTTP | MDN
So I would assume your landing page needs to be:
-href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/$1
+href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Status/$1
Although https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/$1
is a 404.
Like: 200 OK - HTTP | MDN
Thanks!