Running an InstallScript Installation Multiple Times

InstallShield 2020

The InstallScript project type offers several options for the behavior of your installation when a target machine already has your product installed and the end user reruns the installation.

Maintenance Experience Settings

Maintenance Experience

When Maintenance UI Is Displayed

Number of Entries Created in Add or Remove Programs


Whenever the installation is rerun



Only when the installation is rerun from the Add or Remove Programs

Multiple—a separate entry for each instance

No uninstall or maintenance



You can select these options from the Maintenance Experience setting in the General Information view.

For the default behavior—the standard option—the maintenance user interface is displayed if end users rerun an installation on machines.

The multi-instance option lets your end users rerun an installation multiple times as a first-time installation rather than as a maintenance installation. By default, this option lets end users install the product to a different location each time that they run the installation. Each time that they run the installation as a first-time installation, the components that they select (whether directly or by selecting a setup type) are installed.

If one or more instances of your product are present on a machine when an end user reruns the multi-instance installation with a user interface, the installation displays the Qualifying Product(s) Detected dialog. This dialog enables the end user to select the instance to which the update should be applied. However, if the end user reruns the installation silently, the installation suppresses the Qualifying Product(s) Detected dialog and creates a new instance on the machine.

Project:For information on multiple-instance support in Basic MSI projects, see Installing Multiple Instances of Products.