This might help you The app.config file is not supposed to be edited by the application. One way to tell that's the case is to think about where it is located - next to the executable file in a folder that (by default) is not writeable by the user or the user's apps (program files). I would say if it is something the user is modifying, it should be stored in settings.
Enterprise Library: Redirecting connectionStrings section does not add new ConnectionStrings to ConfigurationManager.Con
help you fix your problem Actually, ConfigurationManager.ConnectionStrings does not know anything about Enterprise Library infrastructure. By default, sections cannot be redirected with Enterprise Library's ConfigurationSource. You should use configSource attribute, which is feature of .NET Framework, not Enterprise Library.