尝试创建X类型的控制器时发生错误。请确保该控制器具有无参数构造函数

Question

I'm working on an asp.net mvc project where I've created a partial view with some dropdowns. These are populated with ajax, and should work as a filter. (Not really relevant to my question, I guess, but nice to know anyhow).

A problem occurrs when trying to invoke the partial view, saying the following: An error occurred when trying to create a controller of type 'Project.Name.Web.Controllers.PlanFilterController'. Make sure that the controller has a parameterless public constructor. An error occurred when trying to create a controller of type 'Project.Name.Web.Controllers.PlanFilterController'. Make sure that the controller has a parameterless public constructor.

However, my controller does appear to have a parameterless constructor;

public class PlanFilterController : BaseController
    {
        public PlanFilterControllerViewModel Model { get; set; }
        public List<DropDownItem> Items { get; set; }

        public List<ProjectContract> AllProjects { get; set; }
        public List<CustomerContract> AllCustomers { get; set; }
        public List<UnitContract> AllUnits { get; set; }

        private ProjectServiceClient ProjectClient { get; set; }
        private CustomerServiceClient CustomerClient { get; set; }

        public PlanFilterController()
        {
            AllProjects = new List<ProjectContract>();
            AllCustomers = new List<CustomerContract>();
            AllUnits = new List<UnitContract>();

            ProjectClient = new ProjectServiceClient();
            CustomerClient = new CustomerServiceClient();

            AllProjects = ProjectClient.GetProjects().ToList();
            AllCustomers = CustomerClient.GetCustomers().ToList();
            AllUnits = UnitClient.GetUnits(true, "", false).ToList();
        }

        // GET: /PlanFilter/
        [ChildActionOnly]
        public ActionResult FilterControl()
        {

            return PartialView();
        }

        // Populate dropdowns
        public JsonResult GetCascadeCustomers()
        {
            Items = new List<DropDownItem>();

            foreach (var customer in AllCustomers)
            {
                Items.Add(new DropDownItem
                {
                    ItemId = customer.Id,
                    ItemName = customer.Name
                });
            }

            return Json(Items, JsonRequestBehavior.AllowGet);
        }

        public JsonResult GetCascadeProjects()
        {
            Items = new List<DropDownItem>();

            foreach (var project in AllProjects)
            {
                Items.Add(new DropDownItem
                {
                    ItemId = project.Id,
                    ItemName = project.Name
                });
            }

            return Json(Items, JsonRequestBehavior.AllowGet);
        }

        public JsonResult GetCascadeUnits()
        {
            Items = new List<DropDownItem>();

            foreach (var unit in AllUnits)
            {
                Items.Add(new DropDownItem
                {
                    ItemId = unit.Id,
                    ItemName = unit.Name
                });
            }

            return Json(Items, JsonRequestBehavior.AllowGet);
        }
    }

What am I missing here? Also, if someone could please provide the explanation to why this is the case, that would be nice :)

Answer 1

As mentioned in comments, something had happened when I added my service references, and some code was not automatically generated. This again caused the exception mentioned.