While executing ajax get request, getting error.

While executing ajax get request, getting error.

While Executing ajax request, getting following console error :

"GET http://localhost:1879/cardimages/getimage?id=12 500 (Internal Server Error)" 

I am trying to fetch image from dropdown selection in asp.net mvc :

Following is AJAX code :

<script type="text/javascript">

    $(function () {

        $("#ImageId").change(function (evt)

 {

            var DropDownSelectedVal=$("#ImageId :selected").val();

            alert(DropDownSelectedVal);

            if (DropDownSelectedVal !=null)

 {
                alert("Success");


                $.ajax({

                    url: "@Url.Action("GetImage", "CardImages")",

                    type: "Get",
                    
                    dataType: 'json',
                    contentType: "Image",
            
                    data: { id: DropDownSelectedVal },

                    success: function (data) {
                         alert("Success");

                         $("img-upload2").attr('src', data);

                    },

                    error: function (xhr) {

                        alert("Something went wrong, please try again");

                    }

                });

            }

        });

    });

</script>

Following is function in controller :

   public ActionResult GetImage(int id /* drop down value */)
        {
            var cardImage = db.CardImages.Where(x=>x.CityId == id ).FirstOrDefault();
            string dir = ConfigurationManager.AppSettings["UploadFilesPath1"].ToString() + "/";
            string logoPath = GetFileFromFolder(dir, cardImage.CardFileName + cardImage.OriginalFileName);
            if (logoPath != string.Empty)
            {
                Byte[] bytes = System.IO.File.ReadAllBytes(logoPath);
                cardImage.LogoImage = "data:image/jpeg;charset=utf-8;base64," + Convert.ToBase64String(bytes);
            }
          

            //var model = db.CardImages.Find(id); // This is for example put your code to fetch record. 
            //ViewBag.img = (from s in db.CardImages where s.CityId == id select s.CardFileName + s.OriginalFileName);


            return Json(cardImage.LogoImage);
           
        }


And in view this for dropdown i am using 

  @Html.DropDownList("CityId", null,  "Select City", htmlAttributes: new { @class = "form-control", @Id = "ImageId" })


I am getting browser error in alert as Something went wrong and console error as mentioned above.