Having an issue with WIX upgrade

Question

Having an issue with WIX installer upgrade. Previously we had 2 version of installers 1 for per-machine and another for per-user.

Currently we have developed a dual mode

Answer 1

Windows Installer does not upgrade between per user and per machine, or vice versa. If you want this to happen you need to get in front of the install somehow and find out what type is already installed. Trying to do that when the product has been installed for another user (i.e. not the current installing user) is tricky. MsiEnumRelatedProuctsEx can be called a couple of times looking for per machine and per user installs to see what's going on. However there may be issues with you, User A, trying to uninstall a product that was installed per user by User B. If you are the same user it's easier. MsiEnumRelatedProductsEx can be called a couple of times to see if the product is per user or machine (in a launcher maybe) and you can uninstall the product before installing the new upgrade, or at least tell the user to do the uninstall. Anyway, it can be a mess, and the advice to stick with per machine installs is worth taking.

I should also point out that allowing per user AND per machine installs on the same machine is a feature, not a bug.