protected void Application_Start(){AreaRegistration.RegisterAllAreas();WebApiConfig.Register(GlobalConfiguration.Configuration);FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);RouteConfig.RegisterRoutes(RouteTable.Routes);BundleConfig.RegisterBundles(BundleTable.Bundles);//自定义View
            ViewEngines.Engines.Clear();ExtendedRazorViewEngine engine = new ExtendedRazorViewEngine();engine.AddPartialViewLocationFormat("~/Areas/Common/Views/Shared/{0}.cshtml");engine.AddPartialViewLocationFormat("~/Areas/Common/Views/Shared/{0}.vbhtml");ViewEngines.Engines.Add(engine);//Model去除前后空格ModelBinders.Binders.DefaultBinder = new TrimModelBinder();//设置MEF依赖注入容器
            MefConfig.RegisterMef();//初始化EF6的性能监控
            MiniProfilerEF6.Initialize();//初始化DB
            DatabaseInitializer.Initialize();}protected void Application_BeginRequest(){StackExchange.Profiling.MiniProfiler.Start();}protected void Application_EndRequest(){StackExchange.Profiling.MiniProfiler.Stop();}

Found an answer for my question. Thanks all for replies.Database.SetInitializer<MyContext<Label>>(null);
This fixes the problem and disables DB changes tracking in EF.

    public AdminLayoutAttribute(){//TODO: Test//var userRole = new List<UserRole> { new UserRole { Id = 1, UserId = 1, RoleId = 1 } };//var user = new User { Id = 1, LoginName = "admin", LoginPwd = "8wdJLK8mokI=", UserRole = userRole };//SessionHelper.SetSession("CurrentUser", user);var user = SessionHelper.GetSession("CurrentUser") as User;if (user != null){//  using (StackExchange.Profiling.MiniProfiler.StepStatic("AdminLayout")) using (MiniProfiler.Current.Step("AdminLayout")){// Enqueue a jobvar container = System.Web.HttpContext.Current.Application["Container"] as CompositionContainer;UserService = container.GetExportedValueOrDefault<IUserService>();RoleService = container.GetExportedValueOrDefault<IRoleService>();RoleModulePermissionService = container.GetExportedValueOrDefault<IRoleModulePermissionService>();ModuleService = container.GetExportedValueOrDefault<IModuleService>();ModulePermissionService = container.GetExportedValueOrDefault<IModulePermissionService>();PermissionService = container.GetExportedValueOrDefault<IPermissionService>();}}}