DownloadFileAsync downloads a 0KB file

Question

My code looks like this:

    private static WebClient wc = new WebClient;
...
wc.DownloadFileAsync(URL, FilePath);
wc.DownloadProgressChanged += (s, ev) =>
{
    //Do stuff
};
wc.DownloadFileCompleted += (s, ev) =>
{
    //All the rest of the code
};

However, as soon as DownloadFileAsync is executed, the program immediately closes leaving me with a 0KB file instead of the downloaded file (no error occurs). I believe that it just completely ignores DownloadProgressChanged and executes the code inside the brackets. I'm just assuming

You need to show more code of where DownloadFileAsync is called. Your program is likely ending before the download completes. Because this is a console application most likely you just need to change it to a normal `DownloadFile` and move the code in `DownloadFileCompleted` after the download file call. — Scott Chamberlain, Jul 30 '17 at 18:10

score 0 · Accepted Answer · answered Jul 31 '17 at 08:11

As Scott Chamberlain correctly states, your program seemingly ends before DownloadFileCompleted gets called. If this assumption is correct, wait in the main thread until then, like so:

var completed = new AutoResetEvent(false);
wc.DownloadFileAsync(URL, FilePath);
wc.DownloadProgressChanged += (s, ev) =>
{
    //Do stuff
};
wc.DownloadFileCompleted += (s, ev) =>
{
    //All the rest of the code
    completed.Set();
};
completed.WaitOne();

DownloadFileAsync downloads a 0KB file

1 Answers1