Here is output of /var/log/syslog
May 14 03:48:22 ubu systemd[1]: run-rpc_pipefs.mount: Failed to reset devices.list: Operation not permitted
May 14 03:48:22 ubu systemd[1]: Mounting RPC Pipe File System…
May 14 03:48:22 ubu systemd[1]: proc-fs-nfsd.mount: Failed to reset devices.list: Operation not permitted
May 14 03:48:22 ubu mount[455]: mount: /run/rpc_pipefs: permission denied.
May 14 03:48:22 ubu systemd[1]: Mounting NFSD configuration filesystem…
May 14 03:48:22 ubu mount[456]: mount: /proc/fs/nfsd: permission denied.
May 14 03:48:22 ubu systemd[1]: nfs-config.service: Failed to reset devices.list: Operation not permitted
May 14 03:48:22 ubu systemd[1]: Starting Preprocess NFS configuration…
May 14 03:48:22 ubu systemd[1]: run-rpc_pipefs.mount: Mount process exited, code=exited status=32
May 14 03:48:22 ubu systemd[1]: run-rpc_pipefs.mount: Failed with result ‘exit-code’.
May 14 03:48:22 ubu systemd[1]: Failed to mount RPC Pipe File System.
May 14 03:48:22 ubu systemd[1]: Dependency failed for RPC security service for NFS client and server.
May 14 03:48:22 ubu systemd[1]: rpc-gssd.service: Job rpc-gssd.service/start failed with result ‘dependency’.
May 14 03:48:22 ubu systemd[1]: Dependency failed for NFSv4 ID-name mapping service.
May 14 03:48:22 ubu systemd[1]: nfs-idmapd.service: Job nfs-idmapd.service/start failed with result ‘dependency’.
May 14 03:48:22 ubu systemd[1]: Dependency failed for RPC security service for NFS server.
May 14 03:48:22 ubu systemd[1]: rpc-svcgssd.service: Job rpc-svcgssd.service/start failed with result ‘dependency’.
May 14 03:48:22 ubu systemd[1]: proc-fs-nfsd.mount: Mount process exited, code=exited status=32
May 14 03:48:22 ubu systemd[1]: proc-fs-nfsd.mount: Failed with result ‘exit-code’.
May 14 03:48:22 ubu systemd[1]: Failed to mount NFSD configuration filesystem.
May 14 03:48:22 ubu systemd[1]: Dependency failed for NFS server and services.
May 14 03:48:22 ubu systemd[1]: Dependency failed for NFS Mount Daemon.
May 14 03:48:22 ubu systemd[1]: nfs-mountd.service: Job nfs-mountd.service/start failed with result ‘dependency’.
May 14 03:48:22 ubu systemd[1]: nfs-server.service: Job nfs-server.service/start failed with result ‘dependency’.
May 14 03:48:22 ubu systemd[1]: Started Preprocess NFS configuration.