ENC1003 C# Changes made in project will not be applied while the application is running

Try to get the Lastest Version of your Visual Studio and try again, If Persist, Install Visual Studio 2019 v16.4 Preview 2.

Also Check out the following content>> https://developercommunity.visualstudio.com/content/problem/601258/edits-were-made-to-the-code-which-cannot-be-applie.html. You can also track this same issue on ASP.NET Github: https://github.com/aspnet/AspNetCore/issues/13284. We already have a fix for it, which will be available on Visual Studio 16.4 Preview 2

I was facing the same problem in my Visual Studio 2019, and therefore I had to update VS to the latest version and I was good to go.

Hope helps someone :) :)

You can go to build options and select the option to build solution (build->build solution), this should solve the problem and you will able to continue your project in solution mode.