Wolfram seems to be reorganizing its on-line documentation and thereby breaking some links from this site. I learned this today when Saturisk left a comment to one of my answers saying a link I'd made to a documentation page was broken. It turned out to be easy to repair, but I worry that this may be the tip of a broken-link iceberg; that Wolfram may be reorganizing all of its on-line documentation causing many links on site to soon break if they haven't already.
The old link was http://reference.wolfram.com/mathematica/ref/JSON.html
The new link is http://reference.wolfram.com/language/ref/format/JSON.html
The change needed to restore the link was substituting language/ref/format for mathematica/ref.
The old link was made using the Ref button from halirutan's button plug-in, so users of that plug-in should take note and fix their documentation links should they fail to work.
Update
I started checking some of links appearing in rm -rf's list. The all seem to work as is. It seems redirection is working for these links and only old links that need to put into the form
http://reference.wolfram.com/language/ref/format/
are not being redirected. If this finding holds up, then the problem is nowhere as severe as I feared.
P.S. And it's not 'mathematica` that is causing the problem in the broken links -- it's the absence of 'format'. Even
http://reference.wolfram.com/mathematica/ref/format/JSON.html
gets redirected properly. I guess this is why it took so long before a broken link was discovered -- there are really not that many. I apologize for crying "Wolfram" :-)
/format/
logic into the plugin... This is probably lower priority than if it were a site-wide issue w/ WRI. – rm -rf♦ Mar 26 '15 at 5:10