Jquery form action can't changed

Question

form action dynamically changed in locally machine but can't changed/fire in hosting or IIS local server.

My cshtml code is:

@model RetailMaster.POS.Web.ViewModels.BrandTypeViewModel

@using (Ajax.BeginForm(
        "CreateBrandType", "Setup",
        new AjaxOptions { OnFailure = "InsertFail", OnSuccess = "InsertSuccess" },
        new { id = "formAdd" }
    ))
{
    @Html.ValidationSummary();

    <div class="form-group">
        @Html.HiddenFor(m => m.BTID)

        <div class="row">
            <div class="col-md-6 col-sm-6">@Html.LabelFor(m => m.BTName)</div>
            <div class="col-md-6 col-sm-6">@Html.TextBoxFor(m => m.BTName, new { @class = "form-control" })</div>
        </div>
    </div>


    <div class="form-group">
        <p>
            @*All button click event handle by jquery*@
            <input id="btnSave" type="submit" value="Save" name="save" class="btn btn-lg btn-primary" />
            <input id="btnUpdate" type="submit" value="Update" class="btn btn-lg btn-info" />
        </p>
    </div>
}

js code:

$("#btnSave").click(function () {
    var form = $("#formAdd");
    form.attr("action", "/Setup/CreateBrandType");
});


$("#btnUpdate").click(function () {
    var form = $("#formAdd");
    form.attr("action", "/Setup/UpdateBrandType");
});

C# code upder setup controller:

public ActionResult CreateBrandType(BrandTypeViewModel model){}

problem: form action can't changed dynamically. showing error in js console "SyntaxError: JSON.parse: unexpected character of the JSON data"

try these solution but fail, Change form's action attribute

Jquery to change form action

Changing the action of a form with javascript/jquery