WordPress 3.9 update crash

I updated my site (midplainsind.com) to wordpress 3.9 and after installation, the site crashed and now I get the following error when I try to access the dashboard/backend and the frontend as well.

Fatal error: Call to undefined function wp_register_plugin_realpath() in /home/content/11/10846311/html/midplains/wp-settings.php on line 213