The NFS service fails to start due to "Address already in use" error on Red Hat Enterprise Linux 7

Issue

• We tried to restart nfs-server.service. But getting error failed journalctl-xn. In journalctl we are getting these errors:

Mar 15 00:03:42  kernel: svc: creating transport udp[25555]
Mar 15 00:03:42  kernel: svc: svc_create_socket(lockd, 17, 0.0.0.0, port=25555)
Mar 15 00:03:42  kernel: svc: svc_create_socket error = 98
Mar 15 00:03:42  kernel: svc: attempting to unregister lockdv1
kernel: lockd_up: makesock failed, error=-98
rpc.nfsd[xxx]: error starting threads: errno 98 (Address already in use)

• The following error occurs when starting NFS:

# systemctl restart nfs
Job for nfs-server.service failed. See 'systemctl status nfs-server.service' and 'journalctl -xn' for details.