As of ejabberd-17.11, configuration option certfile, which should point to combined PEM file which consists of private key, server certificate and intermediate certificate(s), was replaced with configuration option certfiles, which should point to directory which holds private key, server certificate, and intermediate certificate(s) in separate PEM files. Also, ca_file configuration option was introduced, which should point to "trusted root certificate bundle".
For ejabberd-17.11 and newer, configuration is similar to:
### ======= CERTIFICATES ======== ###
certfiles:
- "/etc/ssl/certs/live/mimar.rs/*.pem"
ca_file: "/usr/local/etc/ssl/cert.pem"