When I test Rackspace Cloud Files, I also get the error:
Error: Empty hostname / CNAME list.
I'm seeing the following in the log:
PHP Warning: array_merge(): Argument #1 is not an array in /var/www/dev.mysite.com/wp-content/plugins/w3-total-cache/lib/W3/AdminActions/CdnActionsAdmin.php on line 377
The function that's failing is action_cdn_test(), somehow it's not getting the CNAME that is entered in the CDN config.
We started seeing transfer queue errors today, so things are feeling very wobbly. We're considering a downgrade to a prior version of W3TC...here's a link to the 0.9.2.11 if anyone's interested: http://downloads.wordpress.org/plugin/w3-total-cache.0.9.2.11.zip
Any word on a fix for this?