I have build two versions of my application installer. A version 1.0.0.0 and a version 1.0.1.0. In a prebuild step the application's executables are spiked with the selected version.
In order to allow downgrades the attribute AllowDowngrades in MajorUpgrade is set to 'yes'.
After installing 1.0.0.0 I upgrade the installation by running the 1.0.1.0 installer. The executables are properly upgraded. Then I run the 1.0.0.0 installer again to downgrade the installation back to 1.0.0.0. The installation completes and the executables with version 1.0.1.0 are removed; But the executables with version 1.0.0.0 are not reinstalled. They are just missing.
I do not understand why this is happening. I could understand if the installer had refused to overwrite newer executables, but why are the newer executables removed? Is there something else I have to do to make downgrades possible?
The beginning of my Product.wxs:
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"
xmlns:util="http://schemas.microsoft.com/wix/UtilExtension">
<!-- Including defines. -->
<?include Defines.wxi ?>
<Product Id="*"
Name="$(var.ProductName) $(var.MajorMinorVersion)"
Language="1033"
Version="$(var.ProductVersion)"
Manufacturer="$(var.Manufacturer)"
UpgradeCode="$(var.UpgradeGuid)">
<Package InstallerVersion="200" Compressed="yes" InstallScope="perMachine" />
<MajorUpgrade Schedule="afterInstallInitialize" AllowDowngrades='yes' AllowSameVersionUpgrades='no' />
...
REINSTALLMODE had to be changed from default omus to amus:
<Property Id="REINSTALLMODE" Value="amus" />
From Microsoft documentation:
o Reinstall if the file is missing or is an older version.
a Force all files to be reinstalled, regardless of checksum or version.
With this change the executables are reinstalled on the downgrade in the right version.