问题
We have developed an application that is distributed through Windows Installer, created with the use of WiX, where our customers can upgrade from any older version to the newest.
Our latest version however, deletes 2 dll's, and this is only rectified through a reinstall.
Details on the NuGet packages
Microsoft.IdentityModel.Protocol.Extensions was upgraded from Nuget Version 1.0.2.206221351 and File version 1.0.20622.1351 to Nuget version 1.0.4.403061554 and File version 1.0.4.54.
Similar changes happened to file versioning of System.IdentityModel.Tokens.Jwt from Nuget version 4.0.2.206221351 to Nuget version 4.0.4.403061554.
So by changing how the File version was calculated, MS effectively changed the version to a downgrade of the previous (from 20622 to 4 on the build version).
Why the dll's are removed on upgrade
Some call it a bug, and some call it a feature, but what happens, is that the MSI has a step where it records all the files that needs to be upgraded, it then uninstalls the current version, and then only installs the files that was unchanged or bumped in version - any downgrades are left out.
Question: How do we get around it?
We are shipping this product to a lot of different customers, with very varied technical skills, so an upgrade better work, or we will be flooded with support issues. Are there anything I can change, without actually disabling features like the ability for the MSI to rollback in case of errors, which I have seen as a trade off for others solving the same issue.
回答1:
You have a few options. One is to change where you schedule RemoveExistingProducts. Another is to use REINSTALLMODE=AMUS instead of the default OMUS. Another is to do version lying on the offending DLLs so that they always get reinstalled. (Author the file element so the version is 65535.0.0.0 or something like that.)
It's an MSI feature... the bug is in Nuget releasing a newer DLL with a lower version #. That breaks MSI's component rules and default file versioning rules.
回答2:
This might help:
https://blogs.msdn.microsoft.com/astebner/2015/11/16/why-windows-installer-removes-files-during-a-major-upgrade-if-they-go-backwards-in-version-numbers/
and basically Chris is correct, and:
The RemoveExistingProducts placement should be before the costing actions which cause the error.
Another alternative is to open the files with Visual Studio and alter the file versions in the resources so that the rules are followed. File version would not affect assembly version. Just run Visual Studio, then File-Open File, and the Resources section will show where you can change the version.
It's also very likely that a repair will restore the missing files because the missing files "break" the product install. That's easy to test. If that is really the case, then it will repair automatically (and just once) if the app starts with a shortcut, or you can arrange for the shortcut to be advertised. If not, I've seen people use MsiProvideComponent () to make sure the files exist because that will do the repair/install.
来源：https://stackoverflow.com/questions/47157021/downgraded-ms-dll-disappears-on-upgrade-windows-installer