One of the advantages of open source software is that it assist in troubleshooting and solving errors in your application.

Recently I ran into the following problem with ASP.NET MVC 2.0 RC.

After some searching I found the following post:

ASP.NET MVC 2 problem with UpdateModel

I downloaded the ASP.NET MVC 2 RC source code, extracted the zip file, located the offending method and commented out the problem:

    public sealed class FormCollection : NameValueCollection, IValueProvider {

        public FormCollection() {
        }

        public FormCollection(NameValueCollection collection) {
            if (collection == null) {
                throw new ArgumentNullException("collection");
            }

            Add(collection);
        }

        public ValueProviderResult GetValue(string name) {

Commented Code
            //if (String.IsNullOrEmpty(name)) {
            //    throw new ArgumentException(MvcResources.Common_NullOrEmpty, "name");
            //}

            string[] rawValue = GetValues(name);
            if (rawValue == null) {
                return null;
            }

            string attemptedValue = this[name];
            return new ValueProviderResult(rawValue, attemptedValue, CultureInfo.CurrentCulture);
        }

        public IValueProvider ToValueProvider() {
            return this;
        }

        #region IValueProvider Members
        bool IValueProvider.ContainsPrefix(string prefix) {
            return ValueProviderUtil.CollectionContainsPrefix(AllKeys, prefix);
        }

        ValueProviderResult IValueProvider.GetValue(string key) {
            return GetValue(key);
        }
        #endregion

        private sealed class FormCollectionBinderAttribute : CustomModelBinderAttribute {

            // since the FormCollectionModelBinder.BindModel() method is thread-safe, we only need to keep
            // a single instance of the binder around
            private static readonly FormCollectionModelBinder _binder = new FormCollectionModelBinder();

            public override IModelBinder GetBinder() {
                return _binder;
            }

            // this class is used for generating a FormCollection object
            private sealed class FormCollectionModelBinder : IModelBinder {
                public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) {
                    if (controllerContext == null) {
                        throw new ArgumentNullException("controllerContext");
                    }

                    return new FormCollection(controllerContext.HttpContext.Request.Form);
                }
            }
        }

    }
}

After the solution was built,  I copied the output to the Libraries folder of the application:

Removed the existing reference to System.Web.Mvc from the MVC Application and created a reference the the System.Web.Mvc in the Libraries folder.

Then I commented out the  System.Web.Mvc GAC-version reference from web.config:

<compilation debug="true">
    <assemblies>
        <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Abstractions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <!--<add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />-->
        <add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Data.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="Microsoft.ReportViewer.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
    </assemblies>
    <buildProviders>
        <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
    </buildProviders>
</compilation>

and updated the /Views/web.config: (Replaced PublicKeyToken=31bf3856ad364e35 with PublicKeyToken=null)

 <pages validateRequest="false"
          pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null, processorArchitecture=MSIL"
          pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null, processorArchitecture=MSIL"
          userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null, processorArchitecture=MSIL">
      <controls>
          <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null, processorArchitecture=MSIL"
               namespace="System.Web.Mvc" tagPrefix="mvc" />
      </controls>
  </pages>      
<!--<pages validateRequest="false" 
       pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" 
       pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" 
       userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <controls>
    <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" 
         namespace="System.Web.Mvc" tagPrefix="mvc" />
  </controls>
</pages>-->