KB4539172 - FIX: Launchpad services fails to start during failover in SQL Server 2019


Assume that you try to install a SQL Server failover cluster that has the Machine Learning Services and Language Extension features enabled on an instance of Microsoft SQL Server 2019. This SQL Server instance has two modes of deployment: Integration Installation with Add Node and Advanced/Enterprise Installation. For the Advanced/Enterprise Installation, a bug in the complete installation step prevents the Launchpad services from starting after a failover occurs.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


This issue is fixed in the following cumulative update for SQL Server:

About cumulative updates for SQL Server:

Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:

NoteĀ Since the fix is part of the SQL Server setup, the CU setup is needed for the fix to take effect. You can do this in one of the following ways:

  • Use the slipstream installation when running from the RTM. Specify /UPDATESOURCE parameter that points to the location with the CU package.

  • Preinstall the CU setup, and then run RTM setup to install a new instance.

  • When the CU runs on a clean box (no SQL), the CU installs the setup binaries. Then, next installation will use the patched setup.

  • When there is already SQL Server RTM installed, the CU would patch it and then next installation will use the patched setup.


Learn about the terminology that Microsoft uses to describe software updates.

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