Internal error

From ChangingRoomWiki

Detected bug in an extension! Hook FBConnectHooks::SpecialListusersHeaderForm failed to return a value; should return true to continue hook processing or false to abort.

Backtrace:

#0 /home/httpd/changingroom.teh.net/wiki/includes/specials/SpecialListusers.php(178): wfRunHooks('SpecialListuser...', Array)
#1 /home/httpd/changingroom.teh.net/wiki/includes/specials/SpecialListusers.php(251): UsersPager->getPageHeader()
#2 [internal function]: wfSpecialListusers(NULL, Object(SpecialPage))
#3 /home/httpd/changingroom.teh.net/wiki/includes/SpecialPage.php(749): call_user_func('wfSpecialListus...', NULL, Object(SpecialPage))
#4 /home/httpd/changingroom.teh.net/wiki/includes/SpecialPage.php(539): SpecialPage->execute(NULL)
#5 /home/httpd/changingroom.teh.net/wiki/includes/Wiki.php(226): SpecialPage::executePath(Object(Title))
#6 /home/httpd/changingroom.teh.net/wiki/includes/Wiki.php(59): MediaWiki->initializeSpecialCases(Object(Title), Object(OutputPage), Object(WebRequest))
#7 /home/httpd/changingroom.teh.net/wiki/index.php(114): MediaWiki->initialize(Object(Title), NULL, Object(OutputPage), Object(User), Object(WebRequest))
#8 {main}