NetWorker NMM SQL VDI backup of Clustered instance fails. Provider cannot be found.

Microsoft SQL Server backups can fail with (NMM) NetWorker Module for Microsoft when the client is a Clustered SQL Server instance.  

The typical error is
 

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

For example, 

(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.

This issue may be caused when a problem occurs during the installation of SQL Server which causes the Microsoft SQL Server Native to not register properly.

For example, in

The program list shows

Microsoft SQL Server Native Client 11.0 – for SQL Server 2012 and 2014

References:  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-exception 

NOTE - this only applies to SQL Server versions up to SQL Server 2017. 
The SQL Server Native Client recommendations have changed in SQL Server 2019 and higher.

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.