MVC 5仍需要System.Web.Helpers吗？

Question

After an upgrade of an MVC 4 application to MVC 5 following the instruction given here , I get the following exception when I try to log in:

Could not load file or assembly 'System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

The source of the error is as follows:

Line 77:         public ActionResult Login(RegisterLoginModel model, string returnUrl)
Line 78:         {
Line 79:             if (ModelState.IsValid && WebSecurity.Login(model.Login.UserName, model.Login.Password, persistCookie: model.Login.RememberMe))
Line 80:             {
Line 81:                 return Redirect(returnUrl);

Here is the assembly load trace:

=== Pre-bind state information ===
LOG: DisplayName = System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
 (Fully-specified)
LOG: Appbase = file:///D:/Users/Bruce/Documents/Projects/Pace/CourseChooser/trunk/CourseChooser.Web/
LOG: Initial PrivatePath = D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\bin
Calling assembly : WebMatrix.WebData, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\web.config
LOG: Using host configuration file: D:\Users\Bruce\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35

And here is the stack trace:

[FileNotFoundException: Could not load file or assembly 'System.Web.Helpers, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.]
   WebMatrix.WebData.SimpleMembershipProvider.CheckPassword(IDatabase db, Int32 userId, String password) +0
   WebMatrix.WebData.SimpleMembershipProvider.ValidateUser(String username, String password) +171
   System.Web.Security.Membership.ValidateUser(String username, String password) +26
   WebMatrix.WebData.WebSecurity.Login(String userName, String password, Boolean persistCookie) +42
   Selector.Controllers.AccountController.Login(RegisterLoginModel model, String returnUrl) in D:\Users\Bruce\Documents\Projects\Pace\CourseChooser\trunk\CourseChooser.Web\Controllers\Account\AccountController.cs:79
   lambda_method(Closure , ControllerBase , Object[] ) +146
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +30
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +197
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +46
   System.Web.Mvc.Async.ActionInvocation.InvokeSynchronousActionMethod() +37
   System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +24
   System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +43
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +68
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +69
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +230
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +68
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +42
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +124
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +27
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +29
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +27
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +48
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +32
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +26
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +40
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +29
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +24
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +27
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +48
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +58
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +30
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +21
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +29
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +23
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9744373
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Can anyone help identify the problem here and how I can go about resolving it?

UPDATE:

I ran the following in NuGet Package Manager Console :

update-package -reinstall

After running this a reference to System.Web.Helpers was added back to my project references, this despite the fact that the guide referenced above says that this has been rebranded and should be removed. With System.Web.Helpers back in the references the project now runs correctly. So the question now is: Is a reference to System.Web.Helpers still required after updating to MVC 5, and if the answer is "No", then why is my project still requiring this reference?

Answer 1

No, it is not generally required.

Your project still requires the reference because you are using WebMatrix.WebData (specifically in your snippet, WebSecurity.Login ), which has a dependency on System.Web.Helpers .