When you run a command like msiexec /x ProductCode , Windows looks up that specific GUID in its registry to find the cached .msi file and execute the removal. Without the correct code, you cannot programmatically uninstall or repair a specific build. 2. Preventing "Double Installations"

It is common to confuse these two, but they serve very different roles:

Unique to a specific "edition" or version of the program.

The is the backbone of your installer’s identity. By understanding when to keep it and when to change it, you ensure a seamless experience for your users—from the first click of "Install" to the final "Uninstall."

Remains the same across all versions of a product. It acts as the "family name" that allows a new installer to find and replace an older version. Why the Product Code Matters 1. Handling Maintenance and Uninstalls

In InstallShield, you can set the Product Code to * or use the "Generate New GUID" button. For Major Upgrades, always ensure a new GUID is generated.

For "Small Updates" or "Minor Upgrades," the Product Code must remain the same. For a "Major Upgrade" (where the old version is completely uninstalled first), the Product Code change. How to Find Your Product Code in InstallShield

Never change a Product Code mid-release. Once a version is "in the wild," that GUID is locked to that version forever.

Navigate to the section in the left-hand pane. Click on General Information .