Naturally, I tried to change HTTP to HTTPS in that URL but was met with a domain mismatch error (followed by a HTTP 403): https://cps.root-x1.letsencrypt.org/ h

Naturally, I tried to change HTTP to HTTPS in that URL but was met with a domain mismatch error (followed by a HTTP 403): https://cps.root-x1.letsencrypt.org/ https://cps.root-x1.letsencrypt.org/ Fortunately, I see that the actual URL linked from letsencrypt.org is https://letsencrypt.org/ISRG-CPS-May-5-2015.pdf https://letsencrypt.org/ISRG-CPS-May-5-2015.pdf Nonetheless, since http://cps.root-x1.letsencrypt.org http://cps.root-x1.letsencrypt.org is out in the wild, that server should have its HTTPS configuration in working order.