error webmin : Failed to open socket family 10

Failed to open socket family 10 : Address family not supported by protocol at /usr/libexec/webmin/miniserv.pl line 557.

This is because you are trying to start Webmin on a system without IPv6 support.
sudo nano /etc/webmin/miniserv.conf

[root@vps0400 ~]# vi /etc/webmin/miniserv.conf
ipv6=0
/etc/webmin/start

Stopping Webmin server in /usr/libexec/webmin

[root@vps0400 ~]# service webmin restart