The problem seems to be the Microsoft.AspNet.FriendlyUrls
After going into nuget and uninstalling the package, as well as commenting out all the places where its referenced, the error went away.
This means that the automatic switching to mobile is gone, but at least my site is up and running now.
What's frustrating is that godaddy help desk and their advanced hosting support claim that they did not run any updates or patches, but four days ago the site was working fine. Of course, I have not made any publishes on my end.