Problem: NFS Server Does Not Start After Upgrade to UCS 4.3



Problem: NFS server does not start after upgrade to UCS 4.3

After upgrade your NFS server does not start and shows the following output:

root@master:~# service nfs-kernel-server status
● nfs-server.service - NFS server and services
   Loaded: loaded (/lib/systemd/system/nfs-server.service; enabled; vendor preset: enabled)
  Drop-In: /lib/systemd/system/nfs-kernel-server.service.d
   Active: inactive (dead) since Mon 2019-02-11 22:06:43 CET; 1min 6s ago
  Process: 769 ExecStopPost=/usr/sbin/exportfs -f (code=exited, status=0/SUCCESS)
  Process: 766 ExecStopPost=/usr/sbin/exportfs -au (code=exited, status=0/SUCCESS)
  Process: 764 ExecStop=/usr/sbin/rpc.nfsd 0 (code=exited, status=0/SUCCESS)
  Process: 743 ExecStart=/usr/sbin/rpc.nfsd $RPCNFSDARGS (code=exited, status=0/SUCCESS)
  Process: 738 ExecStartPre=/usr/sbin/exportfs -r (code=exited, status=0/SUCCESS)
      CPU: 6ms
Feb 11 22:06:43 master systemd[1]: Starting NFS server and services...
Feb 11 22:06:43 master systemd[1]: Stopped NFS server and services.

Furthermore you might see entries in /var/log/syslog:

Feb 11 13:29:42 master nfsdcltrack[27242]: Failed to init database: -13
Feb 11 13:29:42 master kernel: [258455.107012] NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory
Feb 11 13:29:42 master kernel: [258455.163198] nfsd: last server has exited, flushing export cache


During the upgrade a symbolic link has not been properly removed and thus confuses systemd.
To solve do:

cd /etc/systemd/system/
rm -f  nfs-kernel-server.service
systemctl daemon-reload
systemctl start nfs-server