Registry issue when upgrading

Question

The old version of the setup was created with InstallScope="PerMachine". The new version is intended to have InstallScope="PerUser"; it also needs to use the same registry keys as the old version creates.

The problem is that whatever values are stored under these registry keys during the upgrade will be overwritten at the end with the initial values stored by the old version. Even deleting these keys manually before the installation will make them reappear (with the wrong values) after the installation process.

I have tried creating a custom action and specifically delete these keys, but the result is the same.

How can I ensure that the old version does not interfere with the installation process of the new version allowing to delete the old Registry Keys and re-create them?

What I found to be working:

Performing a REPAIR immediately after installing the new version will yield the correct results!

Uninstalling the old version manually before installing the new one will not remove the keys, but will allow to overwrite them with the correct values.

Answer 1

I have to add this as an answer, too long as a comment. I will "evolve" it once you provide more information:

• Why do you want to switch to per-user installation? In the MSI world this is not an ideal way to deploy. An application is usable per-user even if installed per machine. With a per-machine install you simply add the ability to write shared settings that should not be overridden by a user. And your application is easier to upgrade, uninstall, patch and manage overall.

• Here are a few more links to explain some of the problems with per-user setups. They are real, I am only trying to warn people what problems they are most likely going to face (almost certainly going to face):

  • Having an issue with WIX upgrade
  • Understanding “Per-User” or “Per-Machine” context for application Setup packages

• Are you deploying HKCU or HKLM keys? I would not recommend writing any HKCU values from your setup, they should be written by the application itself. A setup is for writing to HKLM and other places that require "elevated rights". It should never be used to write user preferences. There will be interference when you do upgrades (as you have experienced).

• Where is the registry data you speak of stored? In a single MSI component or several? Is there anything else in that component that still needs to be installed without the registry keys? If you can, please add your source WiX file so we can see for sure.

I am sure that we can make all these problems go away if you follow our advice precisely. You are facing a very common MSI problem.

Let me attempt a tentative answer without having all the information:

1. Remove all HKCU registry information from your setup (if you can).
2. Update your application to write these HKCU values itself, and ideally write to a brand new location in the registry instead of the old one. For example HKCU\Software\MyCompany\MyApp\5 instead of HKCU\Software\MyCompany\MyApp. This "decouples" your old and new state, and you got room to maneuver and clean up things.
3. Making your application write the HKCU keys is not a hack, but the right thing to do. It will make your application much more robust and generally easier to QA for yourself and your team. You can "wipe the slate clean" during testing and start over without a reinstall - in order to focus on application testing.
4. Put any remaining HKLM settings in a single WiX component and set a good key path that will never be modified or deleted by the user or any other process. For example: HKLM\Software\MyCompany\MyApp\5\MyAppHKLMKeyPath = 1
5. If you discover that you have to override a value for each user (in other words change something for every user in HKCU), you can do this with this approach which combines what the setup does with the application itself: http://forum.installsite.net/index.php?showtopic=21552 (if this is important, please read the whole, linked thread).

Answer 2

You should define what kind of upgrade you are doing, and if it's a major upgrade then where is it sequenced in your major upgrade element, although...

Probably the main issue is that cross context major upgrades aren't supported by Windows Installer, so if you are doing a major upgrade you will end up with both products installed. That's not an upgrade, that's most likely just a collision. So assuming that you want only one of them to be installed at the end of all this, you will need to uninstall the older per-machine installation and then install the per-user. As to why the uninstall of the per-machine product doesn't remove the registry keys, there are many possible reasons, such as they were created by the app not the MSI, or the component was marked permanent, or the component has another client product on the system - a log of the uninstall might show what's going on.