For parameter "pageIndex" of non nullable type "System. Int32" of method "System. Web. Mvc. ActionResult List (System. String, System. String, Int32, Int32)" in "Biaowu. Areas. Web. Controllers. MaterialController", the parameter dictionary contains a null item. An optional parameter must be a reference type, a nullable type, or declared as an optional parameter. Parameter name: parameters In System Web. Mvc. ActionDescriptor. ExtractParameterFromDictionary(ParameterInfo parameterInfo, IDictionary`2 parameters, MethodInfo methodInfo) In System Web. Mvc. ReflectedActionDescriptor. Execute(ControllerContext controllerContext, IDictionary`2 parameters) In System Web. Mvc. ControllerActionInvoker. InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) In System Web. Mvc. Async. AsyncControllerActionInvoker.< BeginInvokeSynchronousActionMethod>b__36(IAsyncResult asyncResult, ActionInvocation innerInvokeState) In System Web. Mvc. Async. AsyncResultWrapper. WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) In System Web. Mvc. Async. AsyncControllerActionInvoker. EndInvokeActionMethod(IAsyncResult asyncResult) In System Web. Mvc. Async. AsyncControllerActionInvoker. AsyncInvocationWithFilters.< InvokeActionMethodFilterAsynchronouslyRecursive>b__3c() In System Web. Mvc. Async. AsyncControllerActionInvoker. AsyncInvocationWithFilters.<> c__DisplayClass45.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3e()