Certbot Ubuntu package is installed and successfully renewing the certificate. However, since Apache or Nginx are not reloaded the web site still will show an expired certificate.
Option 1 - If you have only a single web site,
then add the following line:
(Change if running apache vs nginx.)
Update the LetsEncrypt cli.ini file:
$ sudo vi /etc/letsencrypt/cli.ini
. . .
deploy-hook = systemctl reload nginx
Option 2 - If you have multiple web sites,
then add for the specific app/site:
So assuming your site config file is at: /etc/letsencrypt/renewal/my.domain.conf
$ sudo vi /etc/letsencrypt/renewal/my.domain.conf
Add the following line:
. . .
renew_hook = systemctl try-reload-or-restart servicename