Throws WebSocketException when launching Chrome

Description

I haven’t tried Puppeteer before and I’m currently struggling a bit with the example code because it fails to launch chromium instance on macOS (throws WebSocketException).

Complete minimal example reproducing the issue

dotnet new console and,

static void Main(string[] args)
{
    var foo = FoobarAsync().Result;
}

static async Task<string> FoobarAsync()
{
    var browserFetcher = new BrowserFetcher();
    await browserFetcher.DownloadAsync(BrowserFetcher.DefaultRevision);
    var launchOptions = new LaunchOptions
    {
        ExecutablePath = browserFetcher.GetExecutablePath(BrowserFetcher.DefaultRevision),
        Headless = true
    };
    using (var browser = await Puppeteer.LaunchAsync(launchOptions))
    {
        var page = await browser.NewPageAsync();
        await page.GoToAsync("http://localhost:5000");
        var pdfOptions = new PdfOptions { Format = PaperFormat.A4, HeaderTemplate = "<h1>HeaderTemplate</h1>", FooterTemplate = "<h1>FooterTemplate</h1>" };
        var pdfData = await page.PdfStreamAsync(pdfOptions);
        return "";
    }
}

Expected behavior:

No exceptions thrown

Actual behavior:

I get an exception as soon as it tries to launch Chromium (... Puppeteer.LaunchAsync(..)). It seems to download Chromium fine, and there is no change if I point ExecutablePath to a local instance of Chrome.

Unhandled Exception: System.AggregateException: One or more errors occurred. (Failed to create connection) ---> PuppeteerSharp.ChromiumProcessException: Failed to create connection ---> System.Net.WebSockets.WebSocketException: Unable to connect to the remote server
   at System.Net.WebSockets.WebSocketHandle.ConnectAsyncCore(Uri uri, CancellationToken cancellationToken, ClientWebSocketOptions options)
   at System.Net.WebSockets.ClientWebSocket.ConnectAsyncCore(Uri uri, CancellationToken cancellationToken)
   at PuppeteerSharp.Transport.WebSocketTransport.CreateDefaultWebSocket(Uri url, IConnectionOptions options, CancellationToken cancellationToken)
   at PuppeteerSharp.Transport.WebSocketTransport.CreateDefaultTransport(Uri url, IConnectionOptions connectionOptions, CancellationToken cancellationToken)
   at PuppeteerSharp.Connection.Create(String url, IConnectionOptions connectionOptions, ILoggerFactory loggerFactory, CancellationToken cancellationToken)
   at PuppeteerSharp.Launcher.LaunchAsync(LaunchOptions options)
   --- End of inner exception stack trace ---
   at PuppeteerSharp.Launcher.LaunchAsync(LaunchOptions options)
   at PuppeteerSharp.Launcher.LaunchAsync(LaunchOptions options)
   at pdf_console.Program.FoobarAsync() in /Users/lgeir/src/pdf-console/Program.cs:line 25
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at pdf_console.Program.Main(String[] args) in /Users/me/src/pdf-console/Program.cs:line 13

Versions

• PuppeteerSharp 1.12.1
• .NET Core 2.2.103
• OS: macOS Mojave (10.14.3)

[lindsve]

Solution: Added 127.0.0.1 to no_proxy environment variable in addition to localhost and other internal domains

[EdgeHeman]

I was getting the same error with below line of code on Windows machine var browser = await Puppeteer.LaunchAsync(new LaunchOptions ());

I tried with below syntax, and error disappears! var browser = await Puppeteer.LaunchAsync(new LaunchOptions {});