Ajax Request returns HTTP error 500, using MVC and $.ajax call with POST?

Question

I've seen several threads about this, and I've tried all the answers (ASP.NET MVC JsonResult return 500)

My ajax request is re-turning a 500 Internal Error. If I debug I never even get to my action.

Here is my ajax call:

$.ajax({
                    url: '@Url.Action("UpdateSortOrder", "FormItems")',
                    data: { itemToUpdateId: item.attr("id"), newParentItemId: parentItemId, newPreviousItemId: previousItemId },
                    type: 'POST',
                    success: function (data) {
                        console.log(data);
                    },
                    error: function (xhr, status, exception) {
                        console.log("Error: " + exception + ", Status: " + status);
                    }
                });

And my action:

[HttpPost]
    public ActionResult UpdateSortOrder(Guid itemToUpdateId, Guid newParentItemId, Guid newPreviousItemId)
    {
        FormItem updatedItem = _formItemService.GetOne(x => x.Id == itemToUpdateId);

        return Json(updatedItem, JsonRequestBehavior.DenyGet);
    }

Using chrome console, these are the response headers from the reply:

HTTP/1.1 500 Internal Server Error Cache-Control: private Content-Type: text/html; charset=utf-8 Server: Microsoft-IIS/7.5 X-AspNetMvc-Version: 3.0 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET Date: Tue, 18 Dec 2012 21:53:41 GMT Content-Length: 17041

Server logs show no substatus codes. Any idea what I am doing wrong here? I've prefer to use POST instead of GET.

The Form Data is being shown as :

itemToUpdateId:18ac5399-342e-4a39-9da1-3281a89501df

newParentItemId:null

newPreviousItemId:null

Which is correct.

I've tried setting the contentType to application/json and traditional = true like in this question: Sending ajax post to mvc with "application/json; charset=utf-8" returns error 500 from vs web developer server

Same error.

Answer 1

Well I was able to figure out what the problem was, there was nothing wrong with my AJAX syntax, or even the action. It was just that my returned object contained a circular reference. I was able to see the actual error in chrome console by clicking on the POST request under Network tab, then viewing the preview tab. This displayed the actual error message.