Google has detected that the SSL / TLS certificate used in "myblog" self-signed, meaning the certificate is issued by your server, not by the Certificate Authority. Your certificate can not be trusted by most browsers because only the Certificate Authority is considered the most trusted source for SSL / TLS certificates. In addition, self-signed certificates indicate that your content has not been authenticated, the content may be changed, and your user's data or browsing behavior may be intercepted by a third party. As a result, many web browsers will block users by displaying a security warning message when your site is accessed. This is done to protect the user's browsing behavior from being intercepted by third parties, which can occur on unsafe sites.