This property contains as its value the upgrade code GUID of the product version that you want this version of your application to replace. When the installation of your current version begins, the MSI engine searches the target system for the upgrade code specified. Upon finding a matching upgrade code—along with other matching upgrade properties—the MSI engine upgrades the target system by installing the new version.

If you added an upgrade entry to the Upgrade Paths tree by browsing for and selecting an .msi file on your system, the upgrade code of that .msi file automatically populates the Upgrade Code property. If the .msi file for the product version that you want to upgrade is not on your system, you can type the upgrade code in this property field.

You can also use the browse button to navigate to an .msi file on your system and populate the Upgrade Code property.