[Solved] ASP.Net Error: Microsoft JScript runtime error: ASP.NET Ajax client-side framework failed to load

Hi

On click of Training Type, Training Module dropdown disappears

if (!Page.IsPostBack)                 
{                     
    GetTrainingType();                     
    GetData();                 
}

Error:

Microsoft JScript runtime error: ASP.NET Ajax client-side framework failed to load.

Microsoft JScript runtime error: 'Sys' is undefined

<system.webServer>
<validation validateIntegratedModeConfiguration="false"/>
<handlers>
    <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
    <remove name="OPTIONSVerbHandler" />
    <remove name="TRACEVerbHandler" />
    <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    <add name="CaptchaImage" verb="GET" path="CaptchaImage.axd" type="MSCaptcha.CaptchaImageHandler, MSCaptcha"/>
</handlers>
</system.webServer>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <div class="row">
            <div class="col-lg-2">
                <label>From Date</label>
                <asp:TextBox ID="txtfrDate" class="form-control daterange-single" required="true" onkeydown="return false" placeholder="Date From" runat="server"></asp:TextBox>
            </div>
 
            <div class="col-lg-2">
                <label>To Date</label>
                <asp:TextBox ID="txttoDate" class="form-control daterange-single" required="true" onkeydown="return false" placeholder="Date To" runat="server"></asp:TextBox>
            </div>
 
            <div class="col-lg-2">
                <div class="form-group">
                    <label>Training Type</label>&nbsp;<span style="color: red">*</span>
                    <asp:DropDownList ID="ddlTrainingType" class="form-control" runat="server"  AutoPostBack="true" OnSelectedIndexChanged="Type_Changed">
                        <asp:ListItem Value="">Select Training Type</asp:ListItem>
                    </asp:DropDownList>
                </div>
            </div>
            <div class="col-lg-2">
                <div class="form-group">
                    <label>Training Module</label>
                    <asp:ListBox ID="lstTrainingModule" runat="server" data-placeholder="Choose Training Module" class="form-control multiselect-full-featured" multiple="multiple" SelectionMode="Multiple" data-fouc=""></asp:ListBox>
                </div>
            </div>
        </div>
    </ContentTemplate>
</asp:UpdatePanel>