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try
            {
                WebClient wc = new WebClient();
            WebClient client = new WebClient();
            string UpdateVersion = client.DownloadString("http://testpage/test.txt");
            }
           catch (Exception ex)
            {
                Label1.content = "Update-check error: please try again later";
            }					

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namespace update
{
    /// <summary>
    /// Interaktionslogik für MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        public MainWindow()
        {
            InitializeComponent();
            BackgroundWorker bgw = new BackgroundWorker();
            bgw.WorkerReportsProgress = true;
            bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);
            bgw.ProgressChanged += new ProgressChangedEventHandler(bgw_ProgressChanged);
            bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
            bgw.RunWorkerAsync();
        }
        static void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            
        }

        static void bgw_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            try
            {
                WebClient wc = new WebClient();
                WebClient client = new WebClient();
                wc.DownloadFile("http://testpage/test.txt", "test.txt");
            }
            catch (Exception ex)
            {
                //Fehler
            }
        }

        private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled == true)
            {
                Label1.Content = "Canceled!";
            }
            else if (e.Error != null)
            {
                Label1.Content = "Error: " + e.Error.Message;
            }
            else
            {
                Label1.Content = "Fertig";
            }
        }
     }
}