I've checked log and found this. It might be because I've upgraded Curl to the latest version (curl.x86_64 0:7.57.0-1.0.cf.rhel6).
7] Please refer to https://curl.haxx.se/libcurl/c/libcurl-errors.html for error code: 77
[Sun Dec 17 04:12:21 PST 2017] Can not connect to https://acme-v01.api.letsencrypt.org/directory to get nonce.
[Sun Dec 17 04:12:21 PST 2017] Can not get domain new authz.
[Sun Dec 17 04:12:21 PST 2017] Please add '--debug' or '--log' to check more details.
[Sun Dec 17 04:12:21 PST 2017] See: https://github.com/Neilpang/acme.sh/wiki/How-to-debug-acme.sh
Should I downgrade it and if so, how do I downgrade?