System: Ubuntu 18.04 Web Server: nginx/1.15.8 ISPConfig 3.1.13 Because of this warning: Code: nginx: [warn] the "ssl" directive is deprecated, use the "listen ... ssl" directive instead in /etc/nginx/sites-enabled/000-ispconfig.vhost:4 I've changed the following directive ssl on; into listen 443 ssl; After restarting the nginx server the ISPConfig's Control panel was not accessible anymore through https and the browser was giving the SSL_ERROR_RX_RECORD_TOO_LONG error. I mention that I have a self signed certificate at the moment of ISPConfig installation. After switching back to ssl on; the Control Panel is accessible again through https. No other modification was necessary. Any advice? Thanks!