How to setup ssl certificate for https?

Question

Apache HTTP Server

I installed the Let's Encrypt ssl certificate to my vps server on Centos 7 via certbot,
but when I open the site, when I click on the message (next to the address bar) "Not secure", the message "This root certificate of the certification authority is not trusted, because it was not found in the CAs trusted root certificate store."

Tell me, what else needs to be done so that the connection is considered "secure"?

Answer 1

Make sure to use the fullchain and not just the end certificate. Pretty common mistake, by the way.

Answer 2

read the documentation to the end.

Answer 3

Add the root from LE to the root store, of course. It is strange, of course, that it is not there. Or, if there is a root, but there is no intermediate (which happens) - add an intermediate one.