Wix Major Upgrade and Install Context Issues

Question

I have a Wix project that I have set to allow major upgrades. I'm using WixUI_Advanced for a choice between per-user and per-machine installs. When I install and upgrade per-user everything works as expected, the installer recognizes an upgrade and there is only one entry in Programs and Features. However when I choose a per-machine install, it starts duplicating entries in Programs and Features (even when both install and upgrade are per-machine and to the same folder).

Looking at the install log file it seems that FindRelatedProducts is executing before the user gets a chance to select a per-machine install, so the installer thinks that the context has changed and won't do an upgrade. I attempted to suppress FindRelatedProducts in InstallUISequence but when I do that the installer still skips FindRelatedProducts in the InstallExecuteSequence.

What are my options at this point?

Answer 1

You could manually execute the FindRelatedProducts action again, after the installation context was selected. Use the MsiDoAction method. I used this approach once and it seemed to work.

Answer 2

A better approach would be to run your own custom action before FindRelatedProducts that would search for a previous version of the product already installed. That custom action should set ALLUSERS to either 1 or to Nothing depending on the scope of that previous version, so that FindRelatedProducts finds it and schedules its upgrade. A good idea would then be to disallow selecting the per-user scope for the user if the previous version was installed per-machine - otherwise the installer may have insufficient privileges to upgrade the previous per-machine installation.

This seems to be the approach taken by InstallShield. If you create an empty test MSI package with the free InstallShield Limited Edition and then de-compile it with Dark, you will see that that custom action is called IsSetAllUsers and located in SetAllUsers.dll.