UpgradeCode |
The "UpgradeCode" property should contain a GUID. It is used to identify a product or product family and MAKEMSI uses it by default to automatically uninstall any already installed version of your product before the install "proper" begins.
See these sections for more information:
The simplest way of supplying one to a MAKEMSI script is to provide it in the product section of a version file, for example (from "TryMe.ver"):
; Guid.UpgradeCode = {7EF333CB-3BB9-457D-831E-8482E50F2999}