The message that I'm getting is that it wasn't able to find this template:

file:///C:/Users/etc/Documents/SCPStuff/SCPTemplate1.vsto

I thought that this might have to do with trusted locations, so I added that folder to the trusted locations. That had no real impact. The code I am using comes directly from an MS document:

https://docs.microsoft.com/en-us/vis...s?view=vs-2019

And, aside from the fact that I get an error message each time...it is actually working. I had some other issues to work through when I originally posted this, but those have been worked through.

A further observation is that this doesn't appear to be a typical error message, though I don't have enough experience with automating Word to know. The error message has a title of "Microsoft Office Customization Manager", and it follows with Installing Customization (in bold), then on the next line, "There was an error during installation."

This set of facts suggests to me that I'm not really running into an error in my VSTO plugin, but an error in that Customization Manager, which I don't even know what that is. So, I'm off to see what I can find on that one.