I need to deploy a patch to an existing MSI based application object.
I have created an .msi file (not .msp) to perform the patch and added
the .msi file to the MSI \ Patches list of the application object and
increased the version number to triger the install of the patch.
However, the msi error code returned is 1636:

This patch package could not be opened. Contact the application vendor to
verify that this is a valid Windows Installer patch package.

Manually installing the patch .msi file is successful.

How does the application object deal with msi patches?
Can it only deploy vendor provided patch files (.msp)?