Yep, Alex, you’re right. The theme support forum had a snippet available to add to the function.php file, and it fixed my problem. http://www.kriesi.at/support/topic/having-problems-after-updating-to-wordpress-4-5-please-read-this-first/
They warn that this is a temporary fix but are working on a permanent one. For now, my site’s working again. Woo! Hoo! Thanks for your help!
Thanks for your response Alex! Unfortunately, no luck yet. I started by disabling each component of W3 Total Cache and refreshed. No result. I then deactivated the plugin. Still no change.
