So I finished with my project and saved it now when I try to knit my file to be an HTML file I get "The system cannot find the file specified" and in the Render section I get this "Error in contrib.url(repos, "source") : trying to use CRAN without setting a mirror calls: . . . eval_with_user_handlers -> eval -> eval -> install.packages -> contrib.url"
what do I do to fix this?