I'm trying to update my table using Ajax Call through this code

```
 var customer = {};
        customer.CustomerId = row.find(".CustomerId").find("span").html();
        customer.Nome = row.find(".Nome").find("span").html();
        customer.Tipo = row.find(".Tipo").find("span").html();
        customer.NCM = row.find(".NCM").find("span").html();
        customer.Contabil = row.find(".Contabil").find("span").html();

        $.ajax({
            type: "POST",
            url: "/Home/UpdateCustomer",
            data: '{customer:' + JSON.stringify(customer) + '}',
            contentType: "application/json; charset=utf-8",
            dataType: "json"
        });
    });

```

But when I click to update the value it returns a System.NullReferenceException, I can't see where I'm doing wrong.

Here's my Controller Code

```
 public ActionResult UpdateCustomer(Customer customer)
    {
        using (CustomersEntities entities = new CustomersEntities())
        {
            Customer updatedCustomer = (from c in entities.Customers
                                        where c.CustomerId == customer.CustomerId
                                        select c).FirstOrDefault();
            updatedCustomer.Nome = customer.Nome;
            updatedCustomer.Tipo = customer.Tipo;
            updatedCustomer.NCM = customer.NCM;
            updatedCustomer.Contabil = customer.Contabil;
            entities.SaveChanges();
        }

        return new EmptyResult();
    }

```