How to get WiX major upgrade working?

Question

I am struggling to enable the major upgrade functionality in WiX.

I want every new version of the installer to be a major upgrade (full uninstall, then new install)

Answer 1

If it's of any use to those who discover this thread, I've also encountered a similar problem which I've just figured out.

In my case (and still having been in early stages of developing my installer), the critical difference was that, between versions, I had switched from a per-user install to a per-machine install. More specifically, I'd added the following line to my Product.wxs:

I'm still getting my head around many of the idiosyncrasies of Windows Installers, but I'd assume that by switching the type of installation in this way would be comparable with shifting to a mutually exclusive stream of versioning in many ways (even enabling two identical versions to be installed in parallel!).

It's a shame that the Windows Control Panel doesn't clearly distinguish between installations which are per-user and all-users.