A jquery / ajax web service call is redirected (302 objects moved), and then 500 unknown webservice names

Question

A jquery / ajax web service call is redirected (302 objects moved), and then 500 unknown webservice names

I struggled with this several times .. I searched, but have not yet received a solution. This is only a problem on the production server. In my development environment, everything works fine.

I am using jQuery / Ajax to update product information based on the Color attribute. for example, the product has colors A and B, the price for color A is different from color B. When the user selects a different color, the price information is also updated.

What I did was add the javascript function first: <script language="javascript" type="text/javascript">

function updateProductVariant() {
                var myval = jQuery("#<%=colorDropDownList.ClientID%>").val();
                jQuery.ajax({
                    type: "POST",
                    url: "/Products.aspx/GetVariantInfoById",
                    data: "{variantId:'" + myval + "'}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",

                    success: function (response) {
                        var obj = jQuery.parseJSON(response.d);

                        jQuery("#<%=lblStockAvailablity.ClientID%>").text(obj.StockMessage);
                        jQuery(".price .productPrice").text(obj.CurrentPrice);
                        jQuery(".price .oldProductPrice").text(obj.OldPrice);
                    }

                });
            }

Then I can register the "onclick" event dropdown list for the "updateProductVariant" function

GetVariantInfoById is a Web method in the codebehind, its also very straightforward：
    [WebMethod]
        public static string GetVariantInfoById(string variantId)
        {

        int id = Convert.ToInt32(variantId);

        ProductVariant productVariant = IoC.Resolve<IProductService>().GetProductVariantById(id);

        string stockMessage = productVariant.FormatStockMessage();

        StringBuilder oBuilder = new StringBuilder();

        oBuilder.Append("{");
        oBuilder.AppendFormat(@"""{0}"":""{1}"",", "StockMessage", stockMessage);
        oBuilder.AppendFormat(@"""{0}"":""{1}"",", "OldPrice", PriceHelper.FormatPrice(productVariant.OldPrice));
        oBuilder.AppendFormat(@"""{0}"":""{1}""", "CurrentPrice", PriceHelper.FormatPrice(productVariant.Price));
        oBuilder.Append("}");
        return oBuilder.ToString();
    }