Minor upgrade

Although a minor upgrade, like a major upgrade, can be distributed as a full MSI, in this chapter we'll focus on the more efficient method of distributing it as a patch file (.msp). In this case, a minor upgrade doesn't uninstall the previous version. It only replaces some existing files or adds new ones. We can use the same OldInstaller project that we did for a major upgrade for our product to update. Here's what its Product element should look like:

    <Product
         Id="3E786878-358D-43AD-82D1-1435ADF9F6EA"
         Name="Awesome Software"
         Language="1033"
         Version="1.0.0.0"
         Manufacturer="Awesome Company"
         UpgradeCode="B414C827-8D81-4B4A-B3B6-338C06DE3A11">

Create a new WiX project and call it MinorUpgradeInstaller. You can reuse the markup from the old installer, but change the Product element's Version attribute. Leave its Id the same.

    <Product
         Id="3E786878-358D-43AD-82D1-1435ADF9F6EA"
         Name="Awesome Software...