Nginx, Let’s Encrypt and Firefox untrusted connection

Let's Encrypt logoToday I received my invite to the Let’s Encrypt beta, so I decided to try it out for one of my websites. I got everything working in Google Chrome, but when I tried to view the site in Firefox I got a warning that the connection was untrusted. It took me some time to find out what the issue was.

If you generate a new certificate with Let’s Encrypt for a domain ( in this post) the following files are created:


I used the file cert.pem for the ssl_certificate and ssl_certificate_key variables in my Nginx virtual host configuration. This works without a problem on Google Chrome, but on Firefox this leads to the untrusted connection warning. To fix this you should use the fullchain.pem file instead of the cert.pem file for the ssl_certificate and ssl_certificate_key variables. If you do that, everything works as it should for Firefox.

I will finish this post with a list of all the SSL related variables I use in my Nginx virtual host configuration:

ssl_certificate /etc/letsencrypt/live/;
ssl_certificate_key /etc/letsencrypt/live/;
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:50m;
ssl_session_tickets off;

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;

ssl_stapling on;
ssl_stapling_verify on;
ssl_trusted_certificate /etc/letsencrypt/live/;
December 1, 2015

Click Here to Leave a Comment Below

Leave a Reply: