Failed to start Vsftpd ftp daemon when disabling ipv6

Issue

• Systemd failed to start up vsftpd daemon at system start up.

Sep 20 11:15:19 xxxxxxxx systemd[1]: Starting Vsftpd ftp daemon...
Sep 20 11:15:22 xxxxxxxx systemd[1]: vsftpd.service: control process exited, code=exited status=1
Sep 20 11:15:22 xxxxxxxx systemd[1]: Failed to start Vsftpd ftp daemon.
Sep 20 11:15:22 xxxxxxxx systemd[1]: Unit vsftpd.service entered failed state.
Sep 20 11:15:22 xxxxxxxx systemd[1]: vsftpd.service failed.

• Try to use the # systemctl start vsftpd command to start up vsftpd but failed.

# systemctl start vsftpd
Job for vsftpd.service failed because the control process exited with error code. See "systemctl status vsftpd.service" and "journalctl -xe" for details.

• listen_ipv6=YES configured in /etc/vsftpd/vsftpd.conf.