What should I do if the SSL certificate is connected, but the browser shows the error “Connection is not secure”?

It may happen even if the SSL certificate is installed on your website. The possible reason is a link with HTTP in its URL added to your web page referring to a website without the SSL certificate. It may be your third-party code or a content (video/image) link to a third-party resource.

For instance, you have noticed the error appears in the browser address bar next to the domain after connecting the SSL certificate. 

When checking the webpage, we can see that the link without HTTPS has been added to the field for uploading videos to Zero Block. It is the source of the error.

To fix the error, you need to connect the SSL certificate to the website from where the link was copied to change the HTTP connection to HTTPS. Or you should find another source with a secure connection.