Problem with Facebook App

[LuigiMdg]

My domain is: https://www.PronosticiIppica.it

I ran this command: Click on the link by Facebook App

It produced this output: Security Error: This website have problem with the security certificate

My web server is (include version): Apache2 + PHP 7.1

The operating system my web server runs on is (include version): Ubuntu 14.04

My hosting provider, if applicable, is: DigitalOcean

I can login to a root shell on my machine (yes or no, or I don’t know): Yes

I’m using a control panel to manage my site (no, or provide the name and version of the control panel): Yes, I’m using VirtualMin (WebMin) and I’ve followed this tutorial: https://www.virtualmin.com/node/38853

[serverco]

your site is misconfigured and doesn’t provide the correct chain, you should add the chain files and reload apache, then it should be fine.

[LuigiMdg]

Rebooted and now work…!
Scuse me but I’m a noob