Assume that you are installing a new SQL Server 2014 instance. Meanwhile, Slipstream Microsoft SQL Server 2014 Service Pack 1 (SP1) and Microsoft SQL Server 2014 SP1 Cumulative Update 1 (CU1) are installed by using /UPDATESOURCE on the new instance Setup command line. When you perform the installation, you may receive the following error message:

This update package could not be opened. Verify that the update package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer update package.
MainEngineThread is returning 1635

Additionally, you may receive the following error message in the SQL Server Error log:

The upgrade cannot be installed by the Windows Installer service because the program to be upgraded may be missing, or the upgrade may update a different version of the program. Verify that the program to be upgraded exists on your computer and that you have the correct upgrade.


Cumulative Update

This issue was first fixed in the following cumulative update of SQL Server:

Cumulative Update 2 for SQL Server 2014 SP1

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


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

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