How to use DetachAsync method of PuppeteerSharp.CDPSession class

You might not be able to access to https://storage.googleapis.com/chromium-browser-snapshots/Win_x64/674921/chrome-win.zip.
If you can't access to that URL, you can try to download a Chromium 77 (or greater) manually, and use the ExecutablePath property to set the Chromium app location.

According to the docs you have ScreenShotDataAsync which returns a byte[]:

byte[] data = await page.ScreenshotDataAsync(scrOpts);

There's also ScreenshotStreamAsync which returns a Stream:

Stream stream = await page.ScreenshotStreamAsync(scrOpts);

This works for me:

var alertMessage = "";
//attach to page during entire page life-cycle (until closed).
//handles the case where an javscript alert comes up during login.
page.Dialog += new EventHandler<DialogEventArgs>(async (sender, args) =>
{
    alertMessage = args.Dialog.Message;
    await args.Dialog.Accept(); //this closes it..
    Log.Information("Popup squashed in Login(): {0}", alertMessage);
    Thread.Sleep(500);
});

You have to be careful with your domain property. If it's not valid, it will be ignored. For what I see there. You might be setting something like http://www.yourdomain.com, when yourdomain.com is expected.

You can use the LaunchOptions.ExecutablePath property. If you use ExecutablePath you don't even need to call BrowserFetcher. It would look something like this:

var options = new LaunchOptions
{
    Headless = true,
    ExecutablePath = "<CHROME.EXE FULL PATH>"
};

using (var browser = await Puppeteer.LaunchAsync(options))
{
}

You don't need to call Dispose if you call CloseAsync. Dispose is just a fire and forget call to CloseAsync. See.

According to the docs you have ScreenShotDataAsync which returns a byte[]:

byte[] data = await page.ScreenshotDataAsync(scrOpts);

There's also ScreenshotStreamAsync which returns a Stream:

Stream stream = await page.ScreenshotStreamAsync(scrOpts);

Yarp Reverse proxy with Direct Forwarding is the answer:

Server code: (ASP.NET core minimal API):

Dictionary<string, string> routes = new();

app.UseRouting();
app.UseEndpoints(endpoints =>
{
    endpoints.Map("/connect/{**catch-all}", async httpContext =>
    {
        var route = httpContext.Request.GetDisplayUrl();

        await app.Services.GetRequiredService<IHttpForwarder>().SendAsync(
            httpContext,
            routes.TryGetValue(Path.GetFileName(new Uri(route).AbsolutePath), out string targetRoute) ? targetRoute : route,
            new HttpMessageInvoker(new SocketsHttpHandler()
            {
                UseProxy = false,
                AllowAutoRedirect = false,
                AutomaticDecompression = DecompressionMethods.None,
                UseCookies = false,
                ActivityHeadersPropagator = new ReverseProxyPropagator(DistributedContextPropagator.Current)
            })
        );
    });
});

app.MapGet("/", async () =>
{
    var b = await Puppeteer.LaunchAsync(new()
    {
        ExecutablePath = browserPath // set your chrome directory
    });

    var id = Path.GetFileName(b.WebSocketEndpoint);

    routes.Add(id, b.WebSocketEndpoint);

    return $"ws://your-server-ip-address/connect/{id}";
});

app.Run();

Client code:

await Puppeteer.ConnectAsync(new() { BrowserWSEndpoint = await httpClient.GetStringAsync("http://your-server-ip-address") })

You don't need those brackets.

await canvas.EvaluateFunctionAsync(@"(e, canvasImage)=> {
  var ctx=e.getContext('2d');
  var img=new Image(); 
  img.onload=function() {
    ctx.drawImage(img,0,0);};
    img.src=canvasImage
  }
}", canvasImage);