Wikimedia Bugzilla is closed!

Easy to reproduce, just visit https://www.mediawiki.org/wiki/Topic:Rysujnjdpyb7661r and you get a 500 error and one-line
  [65700052] 2014-08-29 01:11:29: Fatal exception of type MWException
There was a spike of 15 of these errors in 3 seconds Thursday afternoon SF time.

Note this is different from the 400 bad request "Invalid value was provided for loading flow content" pink errorbox "Fatal exception of type Flow\Exception\InvalidInputException" that you you get from an incorrect URL like
https://www.mediawiki.org/wiki/Topic:Zysujnjdpyb7661r  (first letter changed).

Could be user error, and/or maybe it's a UUID that's found but doesn't have the right characteristics.  (Providing a post or board header UUID as Topic:<UUID> doesn't cause this error.)

Full stack trace follows:

2014-08-28 23:06:52 mw1151 mediawikiwiki: [821fbe65] /wiki/Topic:Rysujnjdpyb7661r   Exception from line 286 of /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Formatter/AbstractQuery.php: Did not load root post Rysujnjdpyb7661r
#0 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Formatter/AbstractQuery.php(209): Flow\Formatter\AbstractQuery->getRootPost(Object(Flow\Model\PostRevision))
#1 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Formatter/TopicListQuery.php(67): Flow\Formatter\AbstractQuery->buildResult(Object(Flow\Model\PostRevision), NULL, Object(Flow\Formatter\TopicRow))
#2 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Block/Topic.php(554): Flow\Formatter\TopicListQuery->getResults(Array)
#3 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Block/Topic.php(470): Flow\Block\TopicBlock->renderTopicAPI(Object(Flow\Templating), Array)
#4 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/View.php(129): Flow\Block\TopicBlock->renderAPI(Object(Flow\Templating), Array)
#5 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Actions/Action.php(88): Flow\View->show(Object(Flow\WorkflowLoader), 'view')
#6 /usr/local/apache/common-local/php-1.24wmf19/extensions/Flow/includes/Actions/Action.php(35): Flow\Actions\FlowAction->showForAction('view')
#7 /usr/local/apache/common-local/php-1.24wmf19/includes/MediaWiki.php(439): Flow\Actions\FlowAction->show()
#8 /usr/local/apache/common-local/php-1.24wmf19/includes/MediaWiki.php(307): MediaWiki->performAction(Object(Article), Object(Title))
#9 /usr/local/apache/common-local/php-1.24wmf19/includes/MediaWiki.php(609): MediaWiki->performRequest()
#10 /usr/local/apache/common-local/php-1.24wmf19/includes/MediaWiki.php(460): MediaWiki->main()
#11 /usr/local/apache/common-local/php-1.24wmf19/index.php(46): MediaWiki->run()
#12 /usr/local/apache/common-local/w/index.php(3): require('/usr/local/apac...')
#13 {main}