'Failed to connect to NetVault kernel' error message after restoring the NVDB to a new installation. (4037727)

'Failed to connect to NetVault kernel' error message after restoring the NVDB to a new installation.

The NetVault Server was reformatted and then reinstalled NVBU from fresh.
Whilst restoring NetVault Database (NVDB) backup to the new NetVault Server, the following error message appeared:

"Failed to connect to NetVault kernel"

The following steps resolved the issue:

1] Make sure that you have installed NVBU in the supported method (if not, then the installation and/or software will not work correctly)?
You need to be logged in as an Administrator/root and no AntiVirus Software running during installation on Windows machines.
Also save the zipped binary on each machine locally in its own folder under C: drive e.g. C:\NV_Downloads and not from the Desktop and uncompress there.
Running the installation from a network share or copying installation files from a network share will cause installation and software issues.
Rebooting Windows machines is a must; otherwise the Software will not run correctly. Further installation information is in the NetVault Install Upgrade Guide on the following link:

https://support.quest.com/netvault-backup/technical-documents

If you have not installed NVBU correctly i.e. as above, then you have to uninstall NVBU (e.g. Windows > Control Panel > Programs and Features), then delete the installation folder (e.g. C:\Program Files (x86)\Quest Software) and lastly reboot the machine.
Then follow the above note for re-installing NVBU.

2] In order to restore the NVDB, you have to make sure that you install the NetVault Backup software with the same NetVault version AND NetVault Name; otherwise you cannot restore the NVDB.
Further information is in the following KBA:

https://support.quest.com/netvault-backup/kb/78685

The NetVault Services will stop and the NetVault Console will crash. This is normal as the NVDB data can only be restored when the NetVault Services has stopped.
Just restart the NetVault Services in the Configurator > Service tab.

Additionally only restore the NVDB from a successful NVDB backup and maybe only restore the bare minimum i.e. Backup Indexes, Media Manager and Schedule Manager.
The rest you can manually setup and is therefore a more reliable installation.
Once all has been installed, restored the NVDB and setup correctly, then perform a NVDB backup.