Installing Multiple Instances of Products

InstallShield 2020

Project:This information applies to Basic MSI projects.

For information on multiple-instance support for InstallScript projects, see Running an InstallScript Installation Multiple Times.

Caution:Creating an installation that lets end users install multiple instances of a product on the same machine and in the same context requires sophisticated authoring and serious commitment on the part of the installation developer. This functionality is recommended for only advanced installation developers.

Windows Installer allows only one instance of a product code to be installed in the machine context and only one instance to be installed in each user context. Windows Installer 3.x and later includes support for a product code–changing transform. This type of transform—called an instance transform—enables the same .msi package to be used to install multiple instances of the same product in the same context because it changes the product code for each instance.

Using the multiple-instance support in InstallShield reduces some of the effort needed to support multiple instances of a product. With InstallShield, you can configure one base installation or patch for a product and then configure multiple instances that correspond with each additional instance that you want to support. At build time, InstallShield creates an instance transform for each instance and streams the instance transforms into the .msi package. At run time, the installation typically displays an instance selection dialog that lets end users specify whether they want to install a new instance or maintain an existing one.

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