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ScriptManager.AsyncPostBackError Event

.NET Framework 4

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

Namespace:  System.Web.UI
Assembly:  System.Web.Extensions (in System.Web.Extensions.dll)
C#
C++
F#
VB
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public event EventHandler<AsyncPostBackErrorEventArgs> AsyncPostBackError
ASP.NET
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<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.

C#
VB
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<%@ Page Language="C#" %>

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

<script runat="server">

    protected void ErrorProcessClick_Handler(object sender, EventArgs e)
    {
        // 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();
    }
    protected void SuccessProcessClick_Handler(object sender, EventArgs e)
    {
        // This handler demonstrates no server side exception.
        UpdatePanelMessage.Text = "The asynchronous postback completed successfully.";
    }

    protected void ScriptManager1_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e)
    {
        ScriptManager1.AsyncPostBackErrorMessage = e.Exception.Message;
    }

</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 ID="ScriptManager1" runat="server" 
            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, 3.5

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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Implementation in a Master Page
I have a ToolScriptManager on the masterpage set up as per the example. When I catch/throw an exception from a content page all works as expected. The event gets fired and I'm able to access and display the error via the Page Manager end_request event.. P roblem is though, that by throwing the exception from the content page causes a HTTPUnhandledException which gets caught in the Global.asax (Application_Error)  $0$0 $0 $0How should this be implemented in this scenario? $0$0 $0 $0Thanks$0 $0 $0$0 $0 $0--- Update ---$0 $0$0 $0 $0OK so I've added Server.ClearError(); to the ScriptManager_AsyncPostBackError method which stops the exception being passed to the Application_Error method in Global.asax$0 $0$0 $0 $0 $0 $0$0 $0 $0 $0
protected void ScriptManager_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e)
{
    ...
    ToolkitScriptManager.AsyncPostBackErrorMessage = _message;
    Server.ClearError();
}
$0 $0$0 $0 $0Still obviously getting an HTTPUnhandledException...$0
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