Question

I’m having trouble getting DownloadProgressChangedEventHandler to fire. I understand that, worst case, the event handler should fire every 64Kb. The URL I’m trying to download data from creates 680Kb of XML data on the fly, but the handler does not fire at all.

Here’s test code that demonstrates the problem. Unfortunately I cannot share the specific URL as it contains proprietary data.

static void Main(string[] args)
{
    Console.WriteLine("Downloading data");
    string url = "https://MyUrlThatRespondsWith680KbOfData";
    string outputPath = @"C:\Temp\DeleteMe.xml";
    using (WebClient webClient = new WebClient())
    {
        webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(webClient_DownloadProgressChanged);
        webClient.DownloadFile(url, outputPath);
    }
    Console.Write("Done");
    Console.ReadKey(true);
}

static void webClient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
    Console.WriteLine("Download progress: " + e.BytesReceived);
}

Answer 1

Your code looks ok, but documentation says “This event is raised each time an asynchronous download makes progress” while you are using synchronous version of the download. Switch to use DownloadFileAsync.