How to Create Update Installer Program

With Actual Installer, you can easily create an installer for your application that performs initial installation on a user's computer. You can also create an update installer, a progam that updates the currently installed version of the application to the latest version.

There are two main installation scenarios:
"Clean (or Initial) Install", is the installation of an application on a computer where it is not yet installed.
"Update Mode Install" is the installation of an app on a computer where it is already installed (for example, an earlier version). In this mode, the installer detects that the app is already installed, and updates it to the latest version by replacing old files (registry entries, and other items) with new ones.

Actual Installer offers the following options for the Update Mode installation - see the "If App is Already Installed" setting on the General / Parameters page:

Uninstall - the currently installed version will be uninstalled before installation
Uninstall Silently - the app will be uninstalled silently (without prompting the user)
Update - the Update Mode will be used for the installation
Allow Multiple Versions - the new version will be installed side by side (for example, in a different folder)
Ask User - the setup program will ask the user for the preferred option

When using the "Uninstall" (or "Uninstall Silently") option, the installer launches the uninstallation of the currently installed version, and waits for it to complete. Then it performs a clean installation.

When using the "Update" option, and the app is already installed, the installer will perform an Update Mode installation. If the app is not installed, the installer will perform a Clean installation.

We recommend using the "Update" option. With this setting, you can use the same project for creating the initial installation and update installers.

TIP: To inform users about new versions of your application, use our update notification program - Actual Updater.

How installer detects that app is already installed

The installer searches for the application GUID (specified on the General / Parameters page) in the uninstall keys of the Registry:
"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Uninstall" - a key for apps installed for the current user only
"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" - a key for apps installed for all users on the computer

Note: the installer writes the application GUID to the Registry only if the following options are selected: "Include Uninstaller" and "Show in the Programs and Features list" (page Installation / Uninstallation). If these options are not selected, then the application will not be registered on Windows, and the update installer program will not be able to detect that the application is already installed.

If the installer does not detect that the app is installed, it will perform a standard (clean) installation.