HTTPS conversion tool
Before performing the conversion, content will be scanned to find any URLs which may not work after conversion i.e. any domains which do not appear to support HTTPS content. After switching to HTTPS, the content included from these sites will no longer display within Moodle for users with secure modern browsers. These problematic domains will be converted, but obviously won't work once the conversion is complete, hence they are reported for audit prior to the conversion process.
There is also a CLI conversion tool. To list domains that need conversion:
php admin/tool/httpsreplace/cli/url_replace.php -l
To perform the conversion:
php admin/tool/httpsreplace/cli/url_replace.php -r --confirm
To view Help:
php admin/tool/httpsreplace/cli/url_replace.php -h