Secure and Nonsecure Items
Internet Explorer: "This page contains both secure and nonsecure items. Do you want to display the nonsecure items?"
Chrome: "This page contains other resources which are not secure. These resources can be viewed by others while in transit, and can be modified by an attacker to change the look of the page."
In Firefox, users will not receive an error. However, the browser will show a red line through the standard golden lock icon. This indicates that the page is displaying secure and non-secure content.
What Do I Do?
To resolve this issue, replace any http:// references on your website with secure references so that the objects are loaded through https://. Any content that cannot be loaded securely should not be referenced on your website if you do not want users to experience this error.