Question

I am working on a App that get data from remote server by using WebClient class. The problem is I cannot distinguish the error is:
(1) Connection timeout
(2) The URL doesn’t exist
(3) No network connection

Here is the code snippet:

WebClient client = new WebClient();
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
client.DownloadStringAsync(new Uri(url, UriKind.Absolute));


void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    if (e.Error == null && !e.Cancelled)
    {

    }
    else
    {
    MessageBox.Show(e.Error.ToString()); // Return System.Net.WebException
    MessageBox.Show(e.Error.Data.Count + ""); // return 0

    /*foreach (DictionaryEntry de in e.Error.Data)
        MessageBox.Show(de.Key + ", " +  de.Value);*/   
    }
}

I need to know the error type of DownloadStringCompletedEventArgs as I am going to display a customized error message to user. Please help, thanks!

Answer 1

You can make use of e.Error.Message, which gives the specific error message

Based on your comment:

I didn’t find any resource which gives the list of all error messages. Check the following:
AsyncCompletedEventArgs.Error and
Exception.Message