Summary

The article discusses when and why the Package Code, Product Code, Upgrade Code, and Version Number should be changed.

Synopsis

This article discusses when and why the Package Code, Product Code, Upgrade Code, and Version Number should be changed.

Discussion

The Package, Product, and Upgrade codes are Globally Unique Identifiers (GUIDs) that help define and uniquely identify a Windows Installer (MSI) installation package. These GUIDs are important when sending upgrades or patches. The Windows Installer Service allows you to deliver your package upgrade in the form of a patch or a major upgrade. When sending these upgrades, you must change these GUIDs accordingly for proper functioning of upgrades and to follow the rules set by the Windows Installer Service for upgrades.

When deploying a major upgrade the Windows Installer will uninstall the existing version of your product and then install the major upgrade. The Product and Package Codes of the original installation must be different from the Product and Package Code of the major upgrade installation.

A minor upgrade delivers the entire MSI package and repairs the current installation. It installs only those qualifying files using MSI's file replacement mechanism without actually uninstalling the previous version.

A patch is different from a minor upgrade in the sense that it only delivers and updates those files that have changed to the target machine. Patches are deployed via .msp files and are not full MSI installations.

Here is a table that lists the GUID that need to be made while sending an upgrade: