The problem

Recently I came across a very old Enfold theme – version 3.6.1. The website would should visitors Not Secure instead of a padlock for SSL/TLS.

The research

Upon investigating the HTML DOM through View Source and Developer Tools in Chrome and Edge, it appeared there was only one http:// resource on an otherwise HTTPS site.

This was the culprit:
<link rel=”profile” href=”http://gmpg.org/xfn/11“>

The solution

To change this to an https link without updating/upgrading the theme, edit wp-content/themes/enfold/framework/php/function-set-avia-frontend.php file.

In this file, you will see http:// link. Change that to
<link rel=”profile” href=”http://gmpg.org/xfn/11“>
and save the file.

Additional changes

For good measure, add a plugin called Better Search and Replace to WordPress. Using that plugin, change all occurrences of http:// to https:// throughout the site.

If you have caching on your WordPress site, remove cache. Close your browser. Open it again. Clear browser cache and visit the website that used to show Not Secure. You are likely to now see a padlock, as you’d expect.

Prior to doing this, I looked up some solutions on https://kriesi.at/support/topic/removing-the-link-to-httpgmpg-orgxfn11-in-enfold/ site.