Fatal error: Call to undefined function get_dirsize() in …

I also got this error

Fatal error: Call to undefined function get_user_count() in G:\websites\server4.localhost\wordpress3_beta1\wp-admin\ms-admin.php on line 21

on SuperAdmin > admin

Almost every page of Superadmin area is showing some error.
Fatal error: Call to undefined function is_subdomain_install() in G:\websites\server4.localhost\wordpress3_beta1\wp-admin\ms-sites.php on line 461

Fatal error: Call to undefined function get_blogs_of_user() in G:\websites\server4.localhost\wordpress3_beta1\wp-admin\ms-users.php on line 261

Fatal error: Call to undefined function is_subdomain_install() in G:\websites\server4.localhost\wordpress3_beta1\wp-admin\ms-options.php on line 107

Fatal error: Call to undefined function get_blogs_of_user() in G:\websites\server4.localhost\wordpress3_beta1\wp-admin\my-sites.php on line 12

I’m getting the same error using Dreamhost:

Fatal error: Call to undefined function get_dirsize() in /demo.andrejcarter.com/wp-admin/includes/ms.php on line 458

Same error on the same line for me. Followed the multi-sites instructions to a “t”. Fatal error: Call to undefined function get_dirsize() in /home/public_html/wordpress/wp-admin/includes/ms.php on line 458

Despite the fact the install says you can put the additional wp-config.php code anywhere in the file, you have to actually put it anywhere before the last two lines of code. Put your custom wp-config.php code before this:

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');

I chose to put my code here at the bottom of my wp-config.php:

/** Enable Multisite features. */
define ('WP_ALLOW_MULTISITE', true  ) ;
define( 'MULTISITE', true );
define( 'VHOST', 'no' );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'mysite.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

/* That's all, stop editing! Happy blogging. */

/** Absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
	define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');

Took me a few tries to figure this out.

Thank you reddshack!!!

Awesome – thanks! Those pesky errors are gone.

Great!

THANK YOU!