Q:

VirtualFileResult file not found when file exists

Maybe I'm not understanding what a VirtualFileResult is, but I'm not sure why it's throwing a FileNotFoundException when the file exists. Here's the code:
if (System.IO.File.Exists(fileName))
{
    FileInfo info = new FileInfo(fileName);

    return File(fileName, FileUtility.GetContentType(fileName), info.Name);
}

(Edit: FileUtility.GetContentType (correctly) returns the Mime type of the file, which in my case is "application/pdf".)
Here's the exception I get: (I removed the file path)
System.IO.FileNotFoundException: Could not find file: [file path removed]
File name: '[file path removed]'
   at Microsoft.AspNet.Mvc.VirtualFileResult.<WriteFileAsync>d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResultAsync>d__56.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResultFilterAsync>d__55.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeAllResultFiltersAsync>d__54.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResourceFilterAsync>d__49.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeAsync>d__44.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Infrastructure.MvcRouteHandler.<RouteAsync>d__6.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Routing.Template.TemplateRoute.<RouteAsync>d__27.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Routing.RouteCollection.<RouteAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.IISPlatformHandler.IISPlatformHandlerMiddleware.<Invoke>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Diagnostics.StatusCodePagesMiddleware.<Invoke>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()

It's seemingly bugging out even though an explicit check was done for whether the file exists or not. I can also manually confirm the file exists.
Maybe I'm not understanding what a VirtualFileResult is (File method returns this). On the documentation here it doesn't really describe what it is.
I'm using ASP.NET 5 RC1.

A:

The method you're looking for is PhysicalFile():
return PhysicalFile(fileName, FileUtility.GetContentType(fileName), info.Name);

Beware, don't use a caller-supplied path with this.

A:

The VirtualFileResult class needs the virtual path to the file in its constructor.
This means you need to provide the path relative to the wwwroot folder because it use HostingEnvironment's WebRootFileProvider.
    private IFileProvider GetFileProvider(IServiceProvider requestServices)
    {
        if (FileProvider != null)
        {
            return FileProvider;
        }

        var hostingEnvironment = requestServices.GetService<IHostingEnvironment>();
        FileProvider = hostingEnvironment.WebRootFileProvider;

        return FileProvider;
    }
}

Check the code on github 

