Category Archives: what is self healing

Why does the package go for Self Healing first time the user launches the Application?

If the package is containing some HKCU entries then the package will always go for self healing for the first time. This happens because the HKCU keys are only installed for the current user present while installing the package and not all the users as it is the property of the HKCU. So, if other user logs in then there is a mismatch between the current system state and the value specified in the MSI package (e.g., a key file is missing), then the related feature is re-installed. This is called the Self Healing.


What is Self Healing

Self-healing is the ability of Windows Installer to detect and repair any critical resources that are
required for the user to successfully launch and use the application. Every resource of a package
is not checked during self-healing. Because self-healing occurs as the application is launched,
exhaustive checking of every resource would lead to excessive wait times.

Earlier we discussed how Windows Installer performs basic actions (install, uninstall, and so on)
on lists of Components. We also discussed how these lists of Components were specified by a
list of Features. Self-healing follows this approach as well.

Self-healing, install-on-demand, and user profile fix-up are all variations on the same
functionality provided by Windows Installer. Windows Installer is asked to find the appropriate
software application when an entry point is activated by a user (usually double-clicking a
shortcut or document type). If Windows Installer finds the software is not yet installed, it will
immediately install it. If the software is installed, it will be verified by self-healing. In both cases,
this happens at the Feature level.