Falha no backup VDI SQL do NetWorker NMM da instância em cluster. Provedor não encontrado.

Os backups do Microsoft SQL Server podem falhar com o (NMM) NetWorker Module for Microsoft quando o client é uma instância em cluster do SQL Server.  

O erro típico é
 

Cannot login to SQL Server --Provider cannot be found. It may not be properly installed.

Por exemplo, 

(pid=30180,2/25/2020 11:13:48 AM) D:/views/nw/19.2/nsr/db_apps/bsmsql/nsrsqlado.cpp(2261): Exiting GetProviderError().
(pid=30180,2/25/2020 11:13:48 AM) COM Error
(pid=30180,2/25/2020 11:13:48 AM) Code = 800a0e7a
(pid=30180,2/25/2020 11:13:48 AM) Code meaning = Unknown error 0x800A0E7A
(pid=30180,2/25/2020 11:13:48 AM) Source = ADODB.Connection

(pid=30180,2/25/2020 11:13:48 AM) Description = Provider cannot be found. It may not be properly installed.

(pid=30180,2/25/2020 11:13:48 AM) D:/views/nw/19.2/nsr/db_apps/bsmsql/nsrsqlado.cpp(1100): Exiting adoOpenConnection(), Exception.
66212 2/25/2020 11:13:48 AM  Cannot login to SQL Server VirtualSQLServerName\Instance01.

Esse problema pode ser causado quando ocorre um problema durante a instalação do SQL Server que faz com que o nativo do Microsoft SQL Server não se registre corretamente.

Por exemplo, em

A lista de programas mostra

o Microsoft SQL Server Native Client 11.0 – para SQL Server 2012 e 2014

Referências: 

https://learn.microsoft.com/en-us/sql/relational-databases/native-client/applications/support-policies-for-sql-server-native-client?view=sql-server-ver15#support-lifecycle-exceptionObservação - isso só se aplica a versões do SQL Server até o SQL Server 2017.  
As recomendações do SQL Server Native Client foram alteradas no SQL Server 2019 e versões posteriores.

STEP 1.  Check registry  

Open Powershell on SQL Server and run,

Get-Childitem  "hklm:\software\microsoft\microsoft sql server"

RESULT:  
If you do not see a Key called "SQLNCL11"  then there is an issue with SQL Native Client.


STEP 2.   Connect to SQL instance using OLE DB Driver 

Open Powershell on SQL Server and run, 
 
$conn = New-Object System.data.oledb.oledbconnection
$conn.ConnectionString = "Provider=SQLNCLI11.1;OLE DB Services = -2;Server=VirtualServer\Instancename ;Trusted_Connection=Yes;"

##  where you will please replace   -  VirtualServer\Instancename  --  with  Actual Cluster server name and Instance name   

$conn.open() 

RESULT:
When Open contains no errors  then continue to next step. 
When Open fails then this confirms that there is a problem with SQL Native Client. 

$conn
$conn.close() 

To resolve this issue,

Run Start, Control Panel, Programs and Features, Uninstall Programs, 
you will see a version of,

Microsoft SQL Server 2012 Native Client 

Action:   Right click and select Repair.