Hello,
Update to the latest version of mediawiki failed when running update script and when displaying pages: Fatal error: Interface 'Psr\Log\LoggerInterface' not found in /var/www/parts-unknown/org/mediawiki/core/includes/debug/logger/Logger.php on line 46
This would be version 1.23.6, although I can't verify it with the Special:Version page, because I get the error above.
home% php --version PHP 5.5.18 (cli) (built: Oct 28 2014 20:09:10) Copyright (c) 1997-2014 The PHP Group Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2014, by Zend Technologies home% mysql --version mysql Ver 15.1 Distrib 5.5.39-MariaDB, for FreeBSD10.1 (amd64) using readline 6.3 home%