FtpWebRequest FTP download with ProgressBar

Trivial example of FTP download using FtpWebRequest with WinForms progress bar:

private void button1_Click(object sender, EventArgs e)
{
    // Run Download on background thread
    Task.Run(() => Download());
}

private void Download()
{
    try
    {
        const string url = "ftp://ftp.example.com/remote/path/file.zip";
        var credentials = new NetworkCredential("username", "password");

        // Query size of the file to be downloaded
        WebRequest sizeRequest = WebRequest.Create(url);
        sizeRequest.Credentials = credentials;
        sizeRequest.Method = WebRequestMethods.Ftp.GetFileSize;
        int size = (int)sizeRequest.GetResponse().ContentLength;

        progressBar1.Invoke(
            (MethodInvoker)(() => progressBar1.Maximum = size));
        
        // Download the file
        WebRequest request = WebRequest.Create(url);
        request.Credentials = credentials;
        request.Method = WebRequestMethods.Ftp.DownloadFile;

        using (Stream ftpStream = request.GetResponse().GetResponseStream())
        using (Stream fileStream = File.Create(@"C:\local\path\file.zip"))
        {
            byte[] buffer = new byte[10240];
            int read;
            while ((read = ftpStream.Read(buffer, 0, buffer.Length)) > 0)
            {
                fileStream.Write(buffer, 0, read);
                int position = (int)fileStream.Position;
                progressBar1.Invoke(
                    (MethodInvoker)(() => progressBar1.Value = position));
            }
        }
    }
    catch (Exception e)
    {
        MessageBox.Show(e.Message);
    }
}

The core download code is based on:
Upload and download a file to/from FTP server in C#/.NET

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To explain why your code does not work:

• You are using size of the target file for the calculation: fileStream.Length – It will always be equal to totalReadBytesCount, hence the progress will always be 100.
• You probably meant to use ftpStream.Length, but that cannot be read.
• Basically with FTP protocol, you do not know size of the file you are downloading. If you need to know it, you have to query it explicitly before the download. Here I use the WebRequestMethods.Ftp.GetFileSize for that.