Ok, so I know my answer is rather late but it may help others. In my case everything went well until all of the sudden I had this error:
[ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index]
System.Collections.ObjectModel.Collection`1.set_Item(Int32 index, T value) +14406551
System.Web.Mvc.Html.LinkExtensions.RouteLink(HtmlHelper htmlHelper, String linkText, String routeName, String protocol, String hostName, String fragment, RouteValueDictionary routeValues, IDictionary`2 htmlAttributes) +89
System.Web.Mvc.T4Extensions.ActionLink(HtmlHelper htmlHelper, String linkText, ActionResult result, Object htmlAttributes, String protocol, String hostName, String fragment) +338
System.Web.Mvc.T4Extensions.ActionLink(HtmlHelper htmlHelper, String linkText, ActionResult result, Object htmlAttributes) +107
ASP._Page_Views_Shared__Layout_cshtml.Execute() in c:\work\[...]\Views\Shared\_Layout.cshtml:29
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +280
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +126
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +196
System.Web.WebPages.WebPageBase.Write(HelperResult result) +89
System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action`1 body) +233
System.Web.WebPages.WebPageBase.PopContext() +291
Castle.DynamicProxy.AbstractInvocation.Proceed() +116
Glimpse.Core.Extensibility.ExecutionTimer.Time(Action action) +85
Glimpse.Core.Extensibility.AlternateMethod.NewImplementation(IAlternateMethodContext context) +186
Castle.DynamicProxy.AbstractInvocation.Proceed() +604
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +378
Castle.Proxies.AsyncControllerActionInvokerProxy.InvokeActionResult_callback(ControllerContext controllerContext, ActionResult actionResult) +21
Castle.DynamicProxy.AbstractInvocation.Proceed() +116
Glimpse.Core.Extensibility.ExecutionTimer.Time(Action action) +85
Glimpse.Core.Extensibility.AlternateMethod.NewImplementation(IAlternateMethodContext context) +186
Castle.DynamicProxy.AbstractInvocation.Proceed() +604
System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +33
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +853420
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +265
System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +837892
System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +28
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +65
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +51
System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +51
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288
In my case the problem was that inside web.config I have added an xmlns attribute to the configuration element:
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
Originally it was just
<configuration>
By deleting the xmlns I got my web.config warnings back but my site is working again and I can continue my work.
[Update]
I wanted to add what I think is the real solution to this problem but I saw that gius bellow already wrote it. So yeah, the issue is a missing <bindingRedirect> in web config:
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>