WiX HowTo: Downgrade a third-party dependency without re-installing?

Question

Background

WiX & the Windows Installer are completely new to me.

In production, we used an MSI (created using WiX) to install our software. The MSI references a third-party assembly (e.g. OtherCompany.ThirdParty.dll, version 2.5).

The next release of our software must reference an older version of the third-party assembly (e.g. OtherCompany.ThirdParty.dll, version 1.7).

While I understand that installing an older version of a dependency is uncommon, it must happen.

So my question is... how do you configure a MSI (generated by WiX) to use an older version of an assembly without having to completely uninstall the existing package?

Options

We have explored the following:

1. Increment the assembly's version
   • it's a third party assembly, and
   • for traceability this is not an option
2. rename the assembly
   • the dependency is being retrieved using NuGet... so this won't be straight forward
3. force existing install to be completely removed (automatically or manually)
   • we don't want configuration information that was collected during the previous installation to be lost, so this isn't an option
4. schedule RemoveExistingProducts before costing
   • not recommended by Microsoft (see: MSDN)
5. custom action: to delete dependency
   • if the installation fails, the application may be left in an undefined state
6. override file version in setup
   • moving forward, this will be error prone
7. changing the REINSTALLMODE
   • From the articles that I have read, it appears that this should only be used as a last resort.
8. use a WIX companion file
   • am still investigating

For Moderators

I am aware that there are other SO posts on this subject. Please note that several of the recommended solutions are incomplete or are error prone.

References

• MSDN: Patching and Upgrades
• MSDN: RemoveExistingProducts Action
• downgrade a library during a msi upgrade
• Why Windows Installer removes files during a major upgrade if they go backwards in version numbers
• MSI Writing Guidelines
• What Every Developer Should Know About MSI Components
• Windows installer deletes versioned file during product upgrade, instead of downgrading it
• MSDN: Windows Installer - File Versioning Rules
• Msiexec REINSTALL=ALL REINSTALLMODE=vamus not reinstalling anything
  • good overview of what is happening under-the-hood
• Forcing an upgrade of a file that is modified during its initial installation
  • this is an older post is from 2009

Answer 1

Some issues are best solved by the application design rather the deployment.

There are two places to save a particular version of a .NET assembly: the GAC or the application folder (or subfolder with probing privatePath). In either case, you might want to use a bindingRedirect.

Also, you can load from a specific location using AppDomain.AssemblyResolve, provided the binding is not successful using the GAC.

General Reference: How the Runtime Locates Assemblies—thanks to @Pressacco.