环境和工具：
CentOS上使用VNCServer
Windows上使用TigerVNCViewer
解决过程：
[root@host ~]# init 3
[root@host ~]# service vncserver restart
Redirecting to /bin/systemctl restart vncserver.service
Failed to restart vncserver.service: Unit not found.
[root@host ~]# rm -rf /var/run/yum.pid.
[root@host ~]# systemctl stop firewalld.service
[root@host ~]# systemctl daemon-reload
[root@host ~]# firewall-cmd --permanent --add-service vnc-server
FirewallD is not running
[root@host ~]# systemctl restart firewalld.service
[root@host ~]# systemctl stop firewalld.service
[root@host ~]# systemctl disable firewalld.service
[root@host ~]# systemctl start vncserver@:1.service
[root@host ~]# yum upgrade
Is this ok [y/d/N]: y
[root@host ~]# vncserver :1
最终效果：
