Protocol-Relative Resource Links
What This Means
URLs that load resources such as images, JavaScript and CSS using protocol-relative links. A protocol-relative link is simply a link to a URL without specifying the scheme (for example, //getasky.com, which is missing https:). It helps save developers time from having to specify the protocol and lets the browser determine it based upon the current connection to the resource. However, this technique is now an anti-pattern with HTTPS everywhere, and can expose some sites to ‘man in the middle’ compromises and performance issues
What Triggers This Issue
This issue is triggered when a URL that loads resources such as images, JavaScript and CSS uses protocol-relative links. For example:
<img src="//getasky.com/froggy.jpg" alt="your site" />How To Fix
Update any resource links to be absolute links including the scheme (HTTPS) to avoid security and performance issues.