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.