Hi Barry,
Having the same issue with some of our WordPress websites.
We found that only certain websites had this issue and these websites all had WP Supercache Installed, although it was deactivated, we noticed that the code it creates was still present in the .htaccess file.
It seems this code conflicted with the Wordfence plugin when we chose the Falcon option and caused this error. So I am wondering if you have a similar issue. Do you have any other cache plugin that is putting data in your htaccess file, is your issue fixed when you remove the code created by the other plugin?
This is happening to all of my sites today, if I am not logged in as an Admin. All I get it a bunch of gibberish code like pictured above when I visit my site.
I first noticed this happening a few days ago, when I was setting up two new sites and tried adding them to Google Webmaster Tools after I had installed WordFence. The preview images they were generating for the sites looked like those above – which had me worried, that Google’s bots were not seeing the site properly.
Now that it is happening on all of my sites, I have no choice but to remove this plugin and try someone else’s.
