AJAX Unexpected Token < JSON at position 4

Question

Everything looks correct with my Ajax call and action method but looks like it's returning HTML, instead of valid JSON. Can someone tell me why I'm getting this error?

Error: parsererror SyntaxError: Unexpected token < in JSON at position 4

[HttpPost]
    public ActionResult UpdateStatus()
    {
        try
        {
            return Json(new { success = true, message = "success!" });
        }
        catch (Exception ex)
        {
            return Json(new { success = false, ex.Message });
        }
    }

        $("#updateStatus").click(function () {
                $.ajax({
                    url: "@Url.Action("UpdateStatus","Home")",
                    type: "post",
                    dataType: "json",
                    cache: false,
                    success: function (response, textStatus, jqXHR) {

                    },
                    error: function (jqXHR, textStatus, errorThrown) {
                        alert("Error: " + textStatus + " " + errorThrown);
                    }
                });
            }
        });

Answer 1

I recently got the same error and changing dataType: "html" fixed the error. My controller method is returning a partial view so my case is a little different.

Answer 2

确保每个输入都有ValidationMessageFor元素

Answer 3

您在catch块中缺少message标签