[c#] The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32'

I am building My first MVC application, I have a table in database containing 3 columns:

1. Id ? primary key
2. Username
3. password

When I am clicking on edit link edit a record, its throwing following exception:

The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Edit(Int32)' in 'MvcApplication1.Controllers.UserController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters

Here is my edit code:

public ActionResult Edit(int id, User collection)
{
    UserDBMLDataContext db = new UserDBMLDataContext();
    var q = from abc in db.User_Login_Details
            where abc.Id == id
            select abc;

    IList lst = q.ToList();

    User_Login_Details userLook = (User_Login_Details)lst[0];

    userLook.Username = collection.UserName;
    userLook.Password = collection.Password;
    db.SubmitChanges();
    return RedirectToAction("Index");                  
}

I had the same error, but for me, the issue was that I was doing the request with a wrong GUID. I missed the last 2 characters.

360476f3-a4c8-4e1c-96d7-3c451c6c86
360476f3-a4c8-4e1c-96d7-3c451c6c865e

This error means that the MVC framework can't find a value for your id property that you pass as an argument to the Edit method.

MVC searches for these values in places like your route data, query string and form values.

For example the following will pass the id property in your query string:

/Edit?id=1

A nicer way would be to edit your routing configuration so you can pass this value as a part of the URL itself:

/Edit/1

This process where MVC searches for values for your parameters is called Model Binding and it's one of the best features of MVC. You can find more information on Model Binding here.

Just change your line of code to

<a href="~/Required/[email protected]">Edit</a>

from where you are calling this function that will pass corect id

in your WebApiConfig >> Register () You have to change to

config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }

Here the routeTemplate, is added with {action}

This might be useful for someone who has everything done right still facing issue. For them "above error may also cause due to ambiguous reference".

If your Controller contains

using System.Web.Mvc;

and also

using System.Web.Http;

It will create ambiguity and by default it will use MVC RouteConfig settings instead of WebApiConfig settings for routing. Make sure for WebAPI call you need System.Web.Http reference only

Is the action method on your form pointing to /controller/edit/1?

Try using one of these:

// the null in the last position is the html attributes, which you usually won't use
// on a form.  These invocations are kinda ugly
Html.BeginForm("Edit", "User", new { Id = Model.Id }, FormMethod.Post, null)

Html.BeginForm(new { action="Edit", controller="User", id = Model.Id })

Or inside your form add a hidden "Id" field

@Html.HiddenFor(m => m.Id)

I was facing the Same Error.

Solution: The name of the variable in the View through which we are passing value to Controller should Match the Name of Variable on Controller Side.

.csHtml (View) :

@Html.ActionLink("Edit", "Edit" , new { id=item.EmployeeId })

.cs (Controller Method):

 [HttpGet]
            public ActionResult Edit(int id)
            {
                EmployeeContext employeeContext = new EmployeeContext();
                Employee employee = employeeContext.Employees.Where(emp => emp.EmployeeId == id).First();
                return View(employee);
            }

You get that error because ASP.NET MVC cannot find an id parameter value to provide for the id parameter of your action method.

You need to either pass that as part of the url, ("/Home/Edit/123"), as a query string parameter ("/Home/Edit?id=123") or as a POSTed parameter (make sure to have something like <input type="hidden" name="id" value="123" /> in your HTML form).

Alternatively, you could make the id parameter be a nullable int (Edit(int? id, User collection) {...}), but if the id were null, you wouldn't know what to edit.

Just add Attribute routing if it is not present in appconfig or webconfig

config.MapHttpAttributeRoutes()

Make the id parameter be a nullable int:

public ActionResult Edit(int? id, User collection)

And then add the validation:

if (Id == null) ...

Just in case this helps anyone else; this error can occur in Visual Studio if you have a View as the open tab, and that tab depends on a parameter.

Close the current view and start your application and the app will start 'Normally'; if you have a view open, Visual Studio interprets this as you want to run the current view.

I also had same issue. I investigated and found missing {action} attribute from route template.

Before code (Having Issue):

config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

After Fix(Working code):

config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );