WiX 3.8 keeping config file state during Major Upgrade

Question

I'm using WiX 3.8 (the latest stable release, I think), and I can't seem to get a config file to not get uninstalled-and-reinstalled during a major upgrade.

There are lots of questions about this on SO -- a lot of answers point to this site as a good answer. However, the suggestion given doesn't work (for me).

What the site says is to place each config file in its own component and mark the file as the key path of the component. Something like this:

  <Component Id="config.xml"
             Guid="*"
             Directory="folder_where_config_file_lives">
         <File Id="config_file"
               Source="$(var.Project.ProjectDir)bin\Release\configFile.xml" 
               KeyPath="yes"/>
  </Component>

Great. Next it says to schedule RemoveExistingProduct after the InstallFiles action, like so:

<InstallExecuteSequence>
     <RemoveExistingProducts After="InstallFiles"/>
 </InstallExecuteSequence>

Problem is, when I compile, I get this error:

The InstallExecuteSequence table contains an action 'RemoveExistingProducts' that is declared in two different locations. Please remove one of the actions or set the Overridable='yes' attribute on one of their elements.

This person also had that problem, but he seems to have solved it. What fixed it for him was adding a scheduling attribute to the , which effectively got rid of the "two different locations" declaration problem (I guess):

        <MajorUpgrade  Schedule="afterInstallInitialize"
                       DowngradeErrorMessage="A newer version of [ProductName] is already installed."/>

So when I substitute the schedule change attribute (which contains a attribute itself, I guess), not only does it not work -- the config file gets removed and replaced during the upgrade -- it causes even more weirdness. My project has a bootstrapper with a lot of MSIs, and although I get log files for the installation of all of the MSIs that are after the MSI that contains the config file, they aren't installed.

Let me repeat that: the logs say that the MSIs are installed, but they aren't. There's probably a rollback somewhere that I can't find in the log files, but reading the MSI log files it looks like the installation went swimminly.

Does anyone know a way for a config file to not be removed-and-reinstalled during a Major Upgrade in Wix 3.8? What I've mentioned above is the best info from the interwebs that I could find, but I've tried pretty much everything on SO to no avail.

PhilDW PhilDW · Accepted Answer · 2017-10-14T00:50:43

The MajorUpgrade element has everything you need, including where the RemoveExistingProducts action is scheduled. Don't add a RemoveExistingProducts into a sequence as well.

RemoveExistingProducts shouldn't be after InstallFiles. It's not clear where that comes from, but the documentation doesn't say that's a choice:

https://msdn.microsoft.com/en-us/library/windows/desktop/aa371197(v=vs.85).aspx

When RemoveExistingProducts is sequenced early (such as after InstallInitialize or InstallValidate) it means that you are effectively uninstalling the old product followed by an install of the new product upgrade, and that means uninstalling the config file and installing the one in the upgrade. The way to retain the config file is to schedule REP afterInstallExecute. This results in an upgrade that is basically a version-rules install of the new product over the older installed one. The version rules mean that if you want updated binaries you must update their file versions. The good news about data files (your config file) is that updated data files won't be replaced:

https://msdn.microsoft.com/en-us/library/windows/desktop/aa370531(v=vs.85).aspx

The older product then gets uninstalled, retaining the resulting set of files.

So sequencing of REP afterInstallExecute in the MajorUpgrade seems to be what you want. A caveat is that you need to follow component rules, which should happen automatically if you have auto-generated * guids in WiX.

WiX 3.8 keeping config file state during Major Upgrade

2 Answers