Data Quality Services (DQS) is a collection of SQL Common Language Runtime (SQLCR) routines that reference Microsoft .NET Framework 4 assemblies. When you install any .NET Framework updates on your computer that affect any such referenced .NET Framework assembly, it leads to a change in the Module Version ID (MVID) of the assembly in the Global Assembly Cache (GAC). This causes a mismatch between the MVIDs of the referenced assembly in GAC and the assembly in SQL Server 2017.
If the .NET Framework update requires you to restart the Data Quality Server computer, the affected SQLCLR assemblies are upgraded automatically to fix the MVID mismatch issue on restarting the Data Quality Server computer. However, for .NET Framework updates that do not require you to restart your Data Quality Server computer, an error occurs due to the mismatch in the MVIDs of the assemblies when you try to connect to a Data Quality Server using a Data Quality Client:
A new version of .NET was installed on this machine. In order to continue to work with DQS please run dqsinstaller.exe –upgradedlls.
To fix this issue, the affected SQLCLR assemblies in SQL Server 2017 must be upgraded. You can do so by running the DQSInstaller.exe file with the upgradedlls command line parameter to skip recreating the DQS databases, and just upgrade the affected assemblies. This ensures that your knowledge bases, data quality projects, and any other data in DQS are preserved.
You must be logged on as a member of the Administrators group on the Data Quality Server computer.
Your Windows user account must be a member of the sysadmin fixed server role in the SQL Server instance where Data Quality Server is installed.
To upgrade SQLCLR Assemblies
Start Command Prompt.
At the command prompt, change your directory to the location where DQSInstaller.exe is available. If you installed the default instance of SQL Server, the DQSInstaller.exe file will be available at C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Binn:
cd C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Binn
At the command prompt, type the following command, and press ENTER:
Rest of the steps are same as steps 2-6 in the Run DQSInstaller.exe from Start Screen, Start Menu or Windows Explorer section in Run DQSInstaller.exe to Complete Data Quality Server Installation.