Why does Chrome say "Your connection to this site is not secure" even if the certificate is valid?
I found what it was. After updating Chrome and restarting it, the lock sign was fine. Chrome did not mark my site as insecure anymore. However, as soon as I accessed my server on another port with a self-signed certificate, and I accepted browsing despite the self-signed certificate warning given in Chrome, my site got marked as insecure, even on the tab where I was accessing the standard port (443).
In my case, some of the images (or another resource) inside my website using http so Chrome (and other browsers) say "Connection is not secure" while Certificate (valid)