Your browser shows a warning symbol and displays a message saying your connection to this site is not fully secure.
When you take a closer look, you may also read the following message:
"Attackers might be able to see the images you're looking at on this site and trick you by modifying them."
What is mixed content?
Mixed content is when there is secure and non-secure content (HTTPS and HTTP) being delivered over SSL to your browser. In other words, not all resources loaded by the website are using the HTTPS protocol.
How to Fix Mixed Content Errors?
Essentially, you need to replace any resource using http:// with https://.