After installation of MW 1.27.1 I am experiencing a non functional search (System is Debian Jessie 8.6). There is an error message in the apache PHP log: [Thu Nov 17 10:22:46.548397 2016] [:error] [pid 21777] [client 192.168.xx.xx:59293] PHP Fatal error: OOUI\\InputWidget cannot use OOUI\\FlaggedElement - it is not a trait in /usr/local/share/mwiki/vendor/oojs/oojs-ui/php/widgets/InputWidget.php on line 11, referer: ...
All other stuff is working fine. How can I fix this?