How do you package a VSTO Word addin for deployment to a 64-bit Windows 10 machine running Microsoft Office 64 bit using WIX? - ms-word

Question

Problem
I can't get 64-bit Word to load (or acknowledge the existence of in any way) an otherwise working Word VSTO add-in.
Discussion
I have a working Word VSTO add-in that I developed using Visual Studio 2017 on a 64-bit Windows 7 machine running Microsoft Office 32 bit. I use a WIX installer to deploy the add-in. I successfully deployed the add-in to a Windows 7 64 bit "master" gold disk that runs 32-bit Office, i.e., the add-in is available to any user who brings up a virtual desktop from the master gold disk. See Nova Sys Eng S.O. answer here for details.
Now, my organization is replacing Win 7 64-bit VDIs running 32-bit Office with Win 10 64-bit VDIs running 64-bit Office. In preparation for this, I created a 64-bit Win 10 development machine, installed Office 64-bit, Visual Studio 2019, the WIX Votive2019 extension, and the WIX toolset. On this development machine, I built a release version of the add-in and installed the MSI on this development machine. When I bring up Word on this development machine, it works fine.
Next, I carried the MSI built on the development machine to the 64-bit Win 10 master gold disk machine (again, running Office 64-bit) and successfully installed the add-in (i.e., the WIX installer finished without error). I also installed the VS 2010 Tools for Office Runtime (10.0.60828 released 2018) on the 64-bit Win 10 master gold disk machine. Just like on the 64-bit Win 7 master gold disk (Office 32-bit), the add-in was installed on the 64-bit Win 10 master gold disk machine in
C:\Program Files (x86)\FooAddIn
and the registry settings are
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\Word\AddIns\FooAddIn]
"FriendlyName"="Foo Add-In"
"Description"="Foo Word Add-In"
"Manifest"="C:\\Program Files (x86)\\FooAddIn\\FooAddIn.vsto|vstolocal"
"LoadBehavior"=dword:00000003
When I bring up Word on the 64-bit Win 10 master gold disk machine, the add-in does not load because, apprently, Word is unaware of its existence, i.e,. when I look at Word Options -> Add-Ins, the add-in is not present at all. When I select COM Add-ins -> GO, the COM ADD-ins dialog also does not show the add-in.
One more item:
On the development machine, the Build Config Manager look like the following, i.e., the Platform for the WIX installer program (FooAddInSetup) is set to x86, and there are no other options available.
Why won't Word acknowledge the existence of my add-in?
Is the fact that the add-in is installed in Program Files (x86) an issue?
Is the fact that the Platform for the WIX setup program is x86 an an issue?

Answer 1

I stumbled across Addins for Office programs may be registered under the \Wow6432Node. The part that helped me is this:
Even though I built the add-in on a 64-bit machine that has 64-bit office, the WIX installer set things up such that when I ran the MSI on the Win 10 64-bit gold disk machine (that has 64-bit Office), it added the reg settings to the HKLM\Software\Wow6432node as though the machine has 32 bit office.
I manually created the same reg key settings under HKLM\Software\Microsoft, and the add-in loaded just fine.
So, I have to figure out what I need to do to the WIX config settings to make it right for a machine that has 64-bit office on it.
BTW, the Microsoft page Registry entries for VSTO Add-ins seems to have it backward: