Often we need to modify application configuration files during installation of the application. Generally to set some application settings, or modify database connection strings etc. We can do this in WIX by using the <util:XmlFile/> custom actions. To use these custom actions we need to reference WIXUtilExtension to the setup project. <util:XmlFile Id="UpdateConnectionString" File="[#FileID]" ElementPath="XPATH" […]