title: WebSocketException: Connection was not upgraded to websocket
body: <p>I am currently trying to work with the <a href="https://github.com/xvrh/puppeteer-dart" rel="nofollow noreferrer">Dart Puppeteer library</a>. I have been running the following piece of code:</p>
  
  <pre><code>  var browser = await puppeteer.connect(browserWsEndpoint: "wss://chrome.browserless.io");
  </code></pre>
  
  <p>Unfortunately when I do run this, I get the following error:</p>
  
  <blockquote>
    <p>WebSocketException: Connection to '<a href="https://chrome.browserless.io:0#" rel="nofollow noreferrer">https://chrome.browserless.io:0#</a>' was not upgraded to websocket</p>
  </blockquote>
  
  <p>I was wondering how i could go about fixing this? Thanks in Advance!</p>