Build error: “The process cannot access the file because it is being used by another process”

Question

I\'ve got a C# webforms app, that until today had been working just swimmingly.

Now today, all of a sudden, every time I try run the app, I get a file l

Answer 1

When I ended the process .Net Core Host, everything built fine. I didn't have to close Visual Studio or do change anything else.