QlikView - Management service fails to start with QVPR hosted on Microsoft SQL Server - System.Exception: Database is not a Publisher database - Found database version: -2

After a service restart of the QlikView Management Service, it stops after few seconds.
Looking into the Management Service logs (by default stored in C:\Programdata\QlikTech\ManagementService\Log) you see the following error message
 
20180516T102116.430+0200 Error Fatal error occurred while initializing repository. System.Exception: Database is not a Publisher database. ||    at QMSBackendDDL.Config.CreateAndPatchDatabase() ||    at QMSBackendInterface.QMSBackend.StartupRepository(Int32 rootLogID, String newConnectionString)

Environment: 
QlikView any version with QVPR (Repository)  stored on Microsoft SQL Server 

There are several possible root cause for this error to occur. 
Basically the real root cause is not in the Error event but few lines above that as highlighted below: 

20180516T102116.414+0200 Information Starting patch process...
20180516T102116.430+0200 Information App code version: 12.20.xxx.9FF09E82FC6CA249DF519F79F8D2DF773370506E
20180516T102116.430+0200 Information Found database version: -2
20180516T102116.430+0200 Information Connection to database failed.
20180516T102116.430+0200 Error Fatal error occurred while initializing repository. System.Exception: Database is not a Publisher database. ||    at QMSBackendDDL.Config.CreateAndPatchDatabase() ||    at QMSBackendInterface.QMSBackend.StartupRepository(Int32 rootLogID, String newConnectionString)

The event with Found database version providing a code error is actually giving the root cause of the problem. 
There are several code error with different meaning: 

0 = Non existent database
0.x-3.98 = Old Publisher
-1 = Not a publisher database
-2 = Failed to connect to Microsoft SQL Server

 

I. In case you get Found database version: -2 it will then mean that the Qlik Management Service is unable to connect to Microsoft SQL Server.
Please make sure you haven't change any configuration such as

• The Username/Password of the user connecting to your Microsoft SQL Server
• The name of the database
• The listening port of your Microsoft SQL Server

If this cannot be corrected the recommendation follows:

• Take a database backup of your QVPR
• Take a backup of C:\Programdata\QlikTech\ManagementService
• Remove/Rename the file qvpr_servername.ini in C:\Programdata\QlikTech\ManagementService (This will reset the connection string and will allow you to start the Qlik Management Service with the QVPR on XML)
• Start the Qlik Management Service and connect to your QMC
• Reconnect back the QMC to your SQL Server with the correct information by going to System -> Setup -> Management Service -> Repository as explained here
• Verify that you have retrieved your tasks and configurations

II. In case the logs register Found database version: -1 and following the steps above does not resolve the issue, it may be necessary to restore a working backup of the SQL QVPR database, or recreate it using the "Migrate Data from Current Repository" option explained in the link above.