Mixed content occurs when initial HTML is loaded over a secure HTTPS connection, but other resources (such as images, videos, stylesheets, scripts) are loaded over an insecure HTTP connection. This is called mixed content because both HTTP and HTTPS content are being loaded to display the same page, and the initial request was secure over HTTPS.

If this is something happening to your WordPress website, then you are in the right place.  This service can fix Mixed Content Error from your WordPress website and make it secure.