
I just wasted several hours debugging a an issue of my own creation.
In WC3 Total Cache I enabled the following CDN setting
Set cookie domain to www.myservrname.com
If using subdomain for CDN functionality, this setting helps prevent new users from sending cookies in requests to the CDN subdomain.
This resulted in the servername being set in the top of the wp-config.php file.
<?php
define(‘COOKIE_DOMAIN’, ‘www.myservname.com); // Added by W3 Total Cache
The end result was I could not login to any of the other domains hosted on my WPMU environment.
The fix was to remove the cookie from wp-config.php and restart my server.
Hopefully I have saved you some time in the future – don’t enable this option on a WPMU blog.








I had the same problem, thanks for posting the solution..