Progress while downloading a large file with HttpClient https://github.com/dotnet/runtime/issues/16681

Download.cs

var client = new HttpClient();

var request = new HttpRequestMessage(HttpMethod.Get, <URL>) { };

var response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);

response.EnsureSuccessStatusCode();

var content = await response.Content.ReadAsStreamAsync();

var size = response?.Content?.Headers?.ContentLength ?? 0;

byte[] fileArray;
byte[] buffer = new byte[16 * 1024];
long total = 0;
using (MemoryStream ms = new MemoryStream())
{
	int read;
	while ((read = await content.ReadAsync(buffer, 0, buffer.Length)) > 0)
	{
		await ms.WriteAsync(buffer, 0, read);

		if (size > 0)
		{
			total += read;
			Progress = (total / (double)size);
		}
	}
	fileArray = ms.ToArray();
}