I have a MVC4 App created in VS 2010 with Umbraco 6 too and I've created a web deploy project which is used by my Team City CI server to deploy my website to a CI environment for testing.
On the CI server the first time I load the homepage (or any page) it loads perfectly fine. However the act of loading a page creates a App_Code folder on my CI server, and after that I get the message "The directory '/App_Code/' is not allowed because the application is precompiled". Removing the App_Code folder means that it once again works for one page load and the folder is created again.
Removing the PrecompiledApp.config file causes my site to not load with a YSOD stating "Object reference not set to an instance of an object." at the following point in the stack trace "Umbraco.Web.UmbracoModule.BeginRequest(HttpContextBase httpContext) +25"
To be clear, I don't have an App_Code folder in my project, and I don't want or need one. All I want is for it to stop creating one automatically upon page load! I've used Umbraco in VS and deployed in the same way many times before, just not with Umbraco 6 and in an MVC project.
Any ideas why App_Code is being automatically created and what I can do to stop it?
Many Thanks
Richard