I Googled the problem and everybody says it has happened when anyone updates the solution from one version to another. But I didn't update my solution, just change the IDE from VS12 to VS13. Is this what creates the problem?
[TypeLoadException: Inheritance security rules violated by type: System.Web.WebPages.Razor.WebPageRazorHost'. Derived types must either match the security accessibility of the base type or be less accessible.]
System.Web.WebPages.Razor.RazorBuildProvider.get_CodeCompilerType() +0
System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) +59
System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() +209
System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +30
System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +9971917
System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +299
System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +103
System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) +165
System.Web.Compilation.BuildManager.GetObjectFactory(String virtualPath, Boolean throwIfNotFound) +33
System.Web.Mvc.BuildManagerWrapper.System.Web.Mvc.IBuildManager.FileExists(String virtualPath) +40
System.Web.Mvc.BuildManagerViewEngine.FileExists(ControllerContext controllerContext, String virtualPath) +54
Microsoft.Web.Mvc.FixedRazorViewEngine.Microsoft.Web.Mvc.IViewEngineProxy.FileExists(ControllerContext controllerContext, String virtualPath) +42
Microsoft.Web.Mvc.ViewEngineFixWorker1.FileExists(ControllerContext controllerContext, String virtualPath) +57
Microsoft.Web.Mvc.<>c__DisplayClass4.<GetPathFromGeneralName>b__0(String path) +66
System.Web.WebPages.DefaultDisplayMode.GetDisplayInfo(HttpContextBase httpContext, String virtualPath, Func2 virtualPathExists) +90
System.Web.WebPages.<>c__DisplayClassb.b__8(IDisplayMode mode) +66
System.Linq.WhereSelectListIterator2.MoveNext() +103
System.Linq.Enumerable.FirstOrDefault(IEnumerable1 source, Func2 predicate) +94
System.Web.WebPages.DisplayModeProvider.GetDisplayInfoForVirtualPath(String virtualPath, HttpContextBase httpContext, Func2 virtualPathExists, IDisplayMode currentDisplayMode, Boolean requireConsistentDisplayMode) +297
System.Web.WebPages.DisplayModeProvider.GetDisplayInfoForVirtualPath(String virtualPath, HttpContextBase httpContext, Func2 virtualPathExists, IDisplayMode currentDisplayMode) +108
Microsoft.Web.Mvc.ViewEngineFixWorker1.GetPathFromGeneralName(ControllerContext controllerContext, List1 locations, String name, String controllerName, String areaName, String cacheKey, String[]& searchedLocations) +653
Microsoft.Web.Mvc.ViewEngineFixWorker1.GetPath(ControllerContext controllerContext, String[] locations, String[] areaLocations, String locationsPropertyName, String name, String controllerName, String cacheKeyPrefix, Boolean useCache, String[]& searchedLocations) +1508
Microsoft.Web.Mvc.ViewEngineFixWorker1.FindView(ControllerContext controllerContext, String viewName, String masterName, Boolean useCache) +329
Microsoft.Web.Mvc.FixedRazorViewEngine.FindView(ControllerContext controllerContext, String viewName, String masterName, Boolean useCache) +66
System.Web.Mvc.<>c__DisplayClassc.<FindView>b__b(IViewEngine e) +68
System.Web.Mvc.ViewEngineCollection.Find(Func2 lookup, Boolean trackSearchedPaths) +182
System.Web.Mvc.ViewEngineCollection.Find(Func2 cacheLocator, Func2 locator) +110
System.Web.Mvc.ViewEngineCollection.FindView(ControllerContext controllerContext, String viewName, String masterName) +329
System.Web.Mvc.ViewResult.FindView(ControllerContext context) +135
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +230
System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +39
System.Web.Mvc.<>c__DisplayClass1a.b__17() +74
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +388
System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +72
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +303
System.Web.Mvc.Async.<>c__DisplayClass2a.b__20() +155
System.Web.Mvc.Async.<>c__DisplayClass25.b__22(IAsyncResult asyncResult) +184
System.Web.Mvc.Async.WrappedAsyncResult1.End() +136
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40
System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +40
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult1.End() +151
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44
System.Web.Mvc.Async.<>c__DisplayClass4.b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult1.End() +151
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +45
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult1.End() +151
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9651116
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155
