2523397 - Error during SWPM Option ‘Database Upgrade Completion’ after SQL Server Upgrade

When doing Post-Upgrade tasks as per SAP Note 683447 after an SQL Server upgrade

Start sapinst.exe and choose the "Database Upgrade Completion" option of the SAP Tools for MS SQL Server, the following error occurs in sapinst.log:

The server principal '<DOMAIN_NAME>\SAPService<SID>' already exists.

Or just

An error occurred while processing option <i>Generic Options > MS SQL Server > Database Tools > Database Upgrade Completion(Last error reported by the step: Errors when executing sql command: [Microsoft][ODBC SQL Server Driver]Associated statement is not prepared
 SOLUTION: If this message is displayed as a warning, you can ignore it. If this is an error, contact SAP support.

•  SQL SERVER 2014

Associated statement is not prepared, MDB-05053, MUT-03025, FCO-00011 , KBA , BC-DB-MSS , SQL Server in SAP NetWeaver Products , Problem