Changing a label text in Global.asax

Question

I have a message zone defined in the master page (an update panel with a label inside). I want to handle all the exceptions globally and I thought I can catch them in the Application_Error event in Global.asax and from there change the label text and update the panel. But the text doesn't refresh, probably because I don't understand correctly the page life cycle. Is it possible to change a label text in the application_error event? This is my code:

void DisplayErrorOnPage(AppException myEx)
{
    System.Web.UI.Page page = System.Web.HttpContext.Current.Handler
        as System.Web.UI.Page;
    if (page != null)
    {
        Label ErrorLabel = page.Master.Master.FindControl("StatusMessage") 
                               as Label;
        ErrorLabel.Text = myEx.Message;
        UpdatePanel up = page.Master.Master.FindControl("StatusMessagePanel") 
                             as UpdatePanel;
        up.Update();
    }
}

void Application_Error(object sender, EventArgs e)
{
    Exception myEx = Server.GetLastError().GetBaseException();

    //if it's a controlled exception, display it on the current page
    //otherwise redirect to an error page
    if (myEx is AppException)
    {
        if (((AppException)myEx).RedirectToErrorPage)
            RedirectToErrorPage(myEx);
        else
            DisplayErrorOnPage((AppException)myEx);
    }
    else
    {
        RedirectToErrorPage(myEx);
    }
}

In the Site.Master the message zone is defined like this:

<asp:UpdatePanel runat="server" UpdateMode="Conditional" ID="StatusMessagePanel">
    <ContentTemplate>
        <asp:Label runat="server" ID="StatusMessage" Text="Message zone" />
    </ContentTemplate>
</asp:UpdatePanel>

Answer 1

The thing is possible ,And why the text does not refresh ? There could be something wrong with your ajax implementation and you will get better answers if you add your page code ! but do you know that Application_Error is an application level state management mechanism ? So be carefull to use Application_Error event to catch application level errors and not user level errors !