Failing to Get Swagger to work on 2 new Windows 10 Pro Computers

I've been using swagger for my APIs for several years using computer in my house. I bought 2 new dell computers and can't get them to work on them. I get same "500 Internal Server Error" message (see image below). I built a new computer and swagger works there. What am I missing?  I've spent over a week working every day trying to figure this out and get it to work on my new Dell computers. Any thoughts? I'd pay someone to help me figure it out with shared screen.