SSL cerificate installed via virtualmin but not working


I just being installed Lets encrypt ssl certificate (domain: via the virtualmin web control.
Eventough all things seem to be executed correctly, when I try to access the website using ssl (, I get the following ssl error: ERR_SSL_PROTOCOL_ERROR

server info:
-ubuntu 14.04.5 LTS
-webpanel: virtualmin 5.04

Could you assist me to solve this problem?

Mohamed Belhassen