I had the same error after creating a subdomain for my hostname and generating a letsencrypt-ssl forit.I was ableto resolve that error by logging in as root via ssh and running
root@hostname# ./scripts/generate_hostname_ssl
then
root@hostname# systemctl start cwpsrv.service
That got cwpsrv.service running, however after that httpd.service didn't want to start, so right now i'm going to try a couple things to get that going (rebuild vhosts, etc). But atleast I'm able to access cwp-admin now.
Best of luck, I'll update this when I find the fix for httpd.service