Windows installer deletes versioned file during product upgrade, instead of downgrading it

Question

We use wix to create our setups. For upgrading, we use major upgrades as demonstrated in this answer by Rob Mensching. (In newer wix versions you can use the MajorUpgrade element.) This normally works well. The old product is removed, then the new product is installed.

However, apparently the above is not completely equivalent to manually uninstalling the old product and then manually installing the new product.

Consider for example the following scenario:

• version 1.0 of our product is released, containing version 5.0 of a thirdparty dll
• version 1.1 of our product is released, containing version 5.1 of the same thirdparty dll
• version 1.2 of our product is released, downgrading to version 5.0 of the thirdparty dll again because we discovered that the new version introduced more problems than it solved.

Apparently with the wix upgrade logic linked above, the 3rdparty dll will disappear when upgrading from release 1.1 to 1.2. A repair is necessary to restore it.

Is there another way to upgrade, which would work for this scenario? I guess what I am looking for is upgrade logic which allows the downgrading of components, by behaving exactly as if one manually uninstalls the old product and then manually installs the new product.

Answer 1

We also encountered this problem where lower-versioned DLLs were not getting reinstalled on a major upgrade. I thought it was strange that the installer would decide which files to install based on the versioning of existing files, then completely uninstall everything, but still only install what what files had been determined to install before uninstalling the old product. This seems like it might be a bug in Windows Installer...

To fix this problem we moved the RemoveExistingProducts action above the CostFinalize action.

I know the documentation on MSDN recommends placing the RemoveExistingProducts afterInstallValidate, and I'm not sure if putting it before the InstallValidate action has any negative side effects for minor upgrades, but we have decided to only perform major upgrades for our products so this solution appears to work for us.

Answer 2

Behaviors like this generally have to do with the sequencing of RemoveExistingProducts. If it occurs late enough, Windows Installer will have figured out that there's a newer version of the .dll on the machine, so version 1.2 doesn't need to install it. However when the RemoveExistingProducts results in removing the .dll, nothing puts it back.

Things to try including changing the sequencing of RemoveExistingProducts, and lying about the version of the .dll in your 1.2 package (report a version number higher than the bad one). The downside of the latter is poor impacts on repairs or patching, as the .dll always looks out of date.

Answer 3

Try to schedule RemoveExistingProducts earlier, right after InstallValidate, and change the value of REINSTALLMODE property to amus. This way the old product will be completely removed before any files from the new product are copied, and a mode will force re-install of the files.