Background: had a working Wordpress 3.7 site at olddomain.com.
I moved it to newdomain.com successfully, and in the process added this to wp-config:
This error also occurs when moving a multisite installation to a new domain if you update all options on the database table (usually wp_options), but forget to change the DOMAIN_CURRENT_SITE line on wp-config.php:
wp_options
DOMAIN_CURRENT_SITE
wp-config.php
define( 'DOMAIN_CURRENT_SITE', 'yourdomain.com' );