The actual work of updating the database is done by the migrate.exe tool. To make the MSI package run it properly turned out to be a bit of a challenge. I first included migrate.exe in the installation package to have it deployed to the bin directory together with the assemblies of the system. There is support for running an exe file as a custom action in the web setup projects. Ufortunately I couldn’t get migrate.exe to work unless the working directory was set to the bin directory. The working directory for custom actions is c:\windows\system32 by default. To handle that, a small vb-script was used.