This has been discussed on the mailing list about 6 weeks ago (though I was not subscribed at that time)
Special:MostLinkedPages appears to be broken:
Fatal error: Call to a member function getPrefixedDBkey() on a non-object in mediawiki/includes/specials/SpecialMostlinked.php on line 64
This is indeed caused by a bug in this PHP file. It can be fixed by changing the original code:
function makeWlhLink( &$title, $caption, &$skin ) { $wlh = SpecialPage::getTitleFor( 'Whatlinkshere', $title->getPrefixedDBkey() ); return $skin->makeKnownLinkObj( $wlh, $caption ); }
to:
function makeWlhLink( &$title, $caption, &$skin ) { $wlh = SpecialPage::getTitleFor( 'Whatlinkshere', $title ); return $skin->makeKnownLinkObj( $wlh, $caption ); }
It took 5 minutes to find and fix the bug, and 55 minutes to submit it to bugzilla (apparently the site seems to be under heavy load). https://bugzilla.wikimedia.org/show_bug.cgi?id=18943
With kind regards, Freek Dijkstra