Symptoms
- The Plesk panel is inaccessible with the error:
ERR_CONNECTION_REFUSED
- The sw-cp-server service is in the failed state with the error below:
sw-cp-serverd[642340]: nginx: [emerg] socket() [::]:8443 failed (97: Address family not supported by protocol)
sw-cp-serverd[642340]: nginx: configuration file /etc/sw-cp-server/config test failed
systemd[1]: sw-cp-server.service: Control process exited, code=exited status=1
systemd[1]: sw-cp-server.service: Failed with result 'exit-code'. - The IPv6 interface has been recently disabled and the server was rebooted.
Cause
The sw-cp-server service is still configured to listen on the IPv6 interface, while IPv6 interface does not exist on the server anymore.
Resolution
- Log into the server via SSH.
- Rename the
/etc/sw-cp-server/conf.d/ipv6_ports.inc
configuration file:# mv /etc/sw-cp-server/conf.d/ipv6_ports.inc /etc/sw-cp-server/conf.d/ipv6_ports.inc.back
- Execute the commands below one by one to restart
sw-engine
andsw-cp-server
services:# systemctl restart sw-cp-server
# systemctl restart sw-engine