Mosquitto broker certification issue

Hey there. I want to provide certification to my broker. but after starting I got an error which says Unable to load certificate what should I do?

listener 8883
certfile /etc/letsencrypt/live/domainname/cert.pem
keyfile /etc/letsencrypt/live/domainname/privkey.pem

Error: Unable to load CA certificates. Check cafile and certfile . EXIT CODE 1.

Answered in Management Center restarting broker?