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ScriptManager.AsyncPostBackError Event

Occurs when there is a page error during an asynchronous postback.

Namespace:  System.Web.UI
Assembly:  System.Web.Extensions (in System.Web.Extensions.dll)

'Declaration
Public Event AsyncPostBackError As EventHandler(Of AsyncPostBackErrorEventArgs)
<asp:ScriptManager OnAsyncPostBackError="EventHandler" />

The AsyncPostBackError event is raised when there is a page error during asynchronous postbacks. How errors on the server are sent to the client depends on the AllowCustomErrorsRedirect property, the AsyncPostBackErrorMessage property, and the custom errors section of the Web.config file.

The following example shows how to handle the AsyncPostBackError event to set the AsyncPostBackErrorMessage property (which is sent to the client) to the server exception error message.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

    Protected Sub ErrorProcessClick_Handler(ByVal sender As Object, ByVal e As EventArgs)
        'This handler demonstrates an error condition. In this example
        ' the server error gets intercepted on the client and an alert is shown. 
        Throw New ArgumentException()

    End Sub

    Protected Sub SuccessProcessClick_Handler(ByVal sender As Object, ByVal e As EventArgs)
        'This handler demonstrates no server side exception.
        UpdatePanelMessage.Text = "The asynchronous postback completed successfully."        
    End Sub

    Protected Sub ScriptManager1_AsyncPostBackError(ByVal sender As Object, ByVal e As System.Web.UI.AsyncPostBackErrorEventArgs)
        ScriptManager1.AsyncPostBackErrorMessage = e.Exception.Message
    End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>PageRequestManager endRequestEventArgs Example</title>
    <style type="text/css">
    body {
        font-family: Tahoma;
    }
    #AlertDiv{
    left: 40%; top: 40%;
    position: absolute; width: 200px;
    padding: 12px; 
    border: #000000 1px solid;
    background-color: white; 
    text-align: left;
    visibility: hidden;
    z-index: 99;
    }
    #AlertButtons{
    position: absolute;
    right: 5%;
    bottom: 5%;
    }
	</style>
</head>
<body id="bodytag">
    <form id="form1" runat="server">
        <div>
            <asp:ScriptManager runat="server" ID="ScriptManager1" 
            OnAsyncPostBackError="ScriptManager1_AsyncPostBackError">
            </asp:ScriptManager>

            <script type="text/javascript" language="javascript">
                var divElem = 'AlertDiv';
                var messageElem = 'AlertMessage';
                var errorMessageAdditional = 'Please try again.';
                var bodyTag = 'bodytag';
                Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
                function ToggleAlertDiv(visString)
                {
                     if (visString == 'hidden')
                     {
                         $get(bodyTag).style.backgroundColor = 'white';                         
                     }
                     else
                     {
                         $get(bodyTag).style.backgroundColor = 'gray';                         

                     }
                     var adiv = $get(divElem);
                     adiv.style.visibility = visString;

                }
                function ClearErrorState() {
                     $get(messageElem).innerHTML = '';
                     ToggleAlertDiv('hidden');                     
                }
                function EndRequestHandler(sender, args)
                {
                   if (args.get_error() != undefined && args.get_error().httpStatusCode == '500')
                   {
                       var errorMessage = args.get_error().message
                       args.set_errorHandled(true);
                       ToggleAlertDiv('visible');
                       $get(messageElem).innerHTML = '"' + 
                                errorMessage + '" ' + errorMessageAdditional;
                   }

                }
            </script>
            <asp:UpdatePanel runat="Server" UpdateMode="Conditional" ID="UpdatePanel1">
                <ContentTemplate>
                    <asp:Panel ID="Panel1" runat="server" GroupingText="Update Panel">
                        <asp:Label ID="UpdatePanelMessage" runat="server" />
                        <br />
                        Last update:
                        <%= DateTime.Now.ToString() %>
                        .
                        <br />
                        <asp:Button runat="server" ID="Button1" Text="Submit Successful Async Postback"
                            OnClick="SuccessProcessClick_Handler" OnClientClick="ClearErrorState()" />
                        <asp:Button runat="server" ID="Button2" Text="Submit Async Postback With Error"
                            OnClick="ErrorProcessClick_Handler" OnClientClick="ClearErrorState()" />
                        <br />
                    </asp:Panel>
                </ContentTemplate>
            </asp:UpdatePanel>
            <div id="AlertDiv">
                <div id="AlertMessage">
                </div>
                <br />
                <div id="AlertButtons" >
                    <input id="OKButton" type="button" value="OK" 
                           runat="server" onclick="ClearErrorState()" />
                </div>
           </div>
    </form>
</body>
</html>

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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