I've updated my mediawiki from 1.26.2 to 1.27, the installation process finished ok, but when I try to access I received this error:
Warning: require(/var/app/current/includes/specials/SpecialUserLogin.php): failed to open stream: No such file or directory in /var/app/current/includes/AutoLoader.php on line 81 Fatal error: require(): Failed opening required '/var/app/current/includes/specials/SpecialUserLogin.php' (include_path='/var/app/current/vendor/pear/pear_exception:/var/app/current/vendor/pear/console_getopt:/var/app/current/vendor/pear/pear-core-minimal/src:/var/app/current/vendor/pear/mail_mime:/var/app/current/vendor/pear/mail_mime-decode:/var/app/current/vendor/pear/net_socket:/var/app/current/vendor/pear/net_smtp:/var/app/current/vendor/pear/mail:.:/usr/share/pear:/usr/share/php') in /var/app/current/includes/AutoLoader.php on line 81
I have no idea why is this happening. If I check the files in my server they're there. I'm also having template issues if I choose vector I only get a messed up template, without styling.
I'm using PHP 5.6.
I hope someone can help me.
I just stumbled across this same exact error after upgrading to MW 1.27.
In my case, the SpecialUserlogin.php existed and all of the permissions were right BUT the word login was written in lowercase so the system thought this file didn't exist. So I just renamed the SpecialUserlogin.php to SpecialUserLogin.php and b00m, it worked!
As for your templating issues, check the common.css file. Copy paste everything out of there, so it's empty, if you don't use it. And check that you're calling your style files correctly in your template.