Last modified: 2014-04-23 00:45:20 UTC
We don't think this ever appeared in production. If you enable Flow for a namespace and visit a new page in it, you get Catchable fatal error: Argument 1 passed to Flow\Templating::renderHeader() must be an instance of Flow\Model\Header, null given, called in /home/spage/projects/core/extensions/Flow/includes/Block/Header.php on line 177 and defined in /home/spage/projects/core/extensions/Flow/includes/Templating.php on line 208
Change 116480 had a related patch set uploaded by Matthias Mullie: Header should render even if no header exists yet https://gerrit.wikimedia.org/r/116480
Change 116480 merged by jenkins-bot: Header should render even if no header exists yet https://gerrit.wikimedia.org/r/116480
Not seeing this, so declaring fixed.
This issue is still occurring for me on my own install of Vagrant. I followed the instructions on mediawiki.org for enabling Flow on the User talk namespace, and now when I go to a user talk page I get this error. Reopening as such.