08-30-2017 02:46 PM - edited 08-30-2017 05:46 PM
OK, it's been a really long time since I had to go this far to fix anything remotely as simple as this should have been!
First off, Andreas, you were right; this is what fixed the problem. I ended up downloading the interop file from somewhere on some page to get it to my development machine, then get it to my VM which wasn't as straight-forward as it should have been. Then use GACUTIL to register the interop file to the GAC. So there are three (3) interop files in the GAC: 10, 14 and 15. And because 10, or more accurately, 10.0405.0, is there, at least now my setup will run. (The applications works and is tested, too)
What I still haven't figured out is, why did I need version 10 in the first place. From what I've read, for Office 2013 all I needed would be version 14 and that was always in the GAC. I wonder if I included something, or didn't include something, in the original program development in Visual Studio 2015 that got things out of line. If this problem comes up in every deployment of this program, somebody had to register interop version 10 on every machine on which we deploy this program. I think I saw something in my travels about doing this programitically with an added project in the solution, but I have to find it again. Seems like there would be a simpler way.