It looks like the article got deleted:

select * from querycache where qc_type='Disambiguations' limit 1 OFFSET 471;

+-----------------+----------+--------------+-------------+

+-----------------+----------+--------------+-------------+

+-----------------+----------+--------------+-------------+
1 row in set (0.00 sec)

select page_namespace,page_title from page where page_id='2738390';

Empty set (0.00 sec)

Not going to run a query on archive ar_page_id since there is no index.

Quoting MinuteElectron on IRC :
"What is happening here is that the title object is not being check for being null before being used."

Indeed :

SpecialDisambiguations.php :

function formatResult( $skin, $result ) {

global $wgContLang;
$title = Title::newFromId( $result->value );
$dp = Title::makeTitle( $result->namespace, $result->title );

Next line trigger the error. The article got deleted and we did not check
we had a valid title :)

$from = $skin->makeKnownLinkObj( $title, '' );

r40496 should prevent the fatal error in Linker.php, just not yet live on Wikimedia yet. Marking as resolved.

Code still need to be patched to use linker::link()
Various special pages are still using the old functions.

r40622 fix:

• Special:Disambiguations
• Special:Mostcategories
• SpecialMostlinkedtemplates

Still need to fix the other ones such as Special:Shortpages

ayg wrote:

Fixed in r40626.