I am having similar problem…. this is what is being shown at top of my site after updating today.
define( ‘WPCACHEHOME’, ‘/home/magnific/public_html/goodhealthwithd/wp-content/plugins/wp-super-cache/’ ); //Added by WP-Cache Manager
I logged out of my site and then it would not let me log back in and the only thing that shows up when I type in the URL is a blank page with the above message on it.
I managed to get back in via a favourites page to back office of my wordpress site but do not want to log out again until fixed.
I tried deactivating the pluggin but it has not seemed to have changed the problem and certainly not fixed it.
If anyone has experience this and knows how to fix would appreciate it.