Invalid special page name ""

Backtrace:

#0 /usr/server/www/sprintdoc/includes/Title.php(2038): SpecialPage::getTitleFor(NULL)
#1 /usr/server/www/sprintdoc/includes/Title.php(2123): Title->checkReadPermissions('read', Object(User), Array, true, false)
#2 /usr/server/www/sprintdoc/includes/Title.php(1583): Title->getUserPermissionsErrorsInternal('read', Object(User), true)
#3 /usr/server/www/sprintdoc/includes/Wiki.php(176): Title->getUserPermissionsErrors('read', Object(User))
#4 /usr/server/www/sprintdoc/includes/Wiki.php(593): MediaWiki->performRequest()
#5 /usr/server/www/sprintdoc/includes/Wiki.php(503): MediaWiki->main()
#6 /usr/server/www/sprintdoc/index.php(58): MediaWiki->run()
#7 {main}