Metro apps in Windows 8 can make use of Web Authentication using the WinRT API.
You may encounter errors while using the AuthenticateAsync method from the WebAuthenticationBroker inside your Metro App.
The Error returned is usually similar, for example
Error returned by WebAuth broker. Error Number: – 2146697211 Error Message: Unknown runtime error.
You must be connected to the internet.
The reason to the above problem is simple, you do not have internet connectivity inside your app.
You can also take these steps to resolve the problem
- Check if your internet connection is configured correctly.
- The request and callback Uri values are correct. Do not omit the callback Uri value, this can also cause this error.
- Make sure you are trying to access the results of the authentication operation after checking the status of the authentication operation.
Lastly, if your problem remains unsolved, explore any documentation form Microsoft regarding the error number available to you. As a last resort, you can also post on the Windows 8 forum.
World Wide Code 
Do you have any experience with this error when using the WebAuthenticationBroker:
WinRTError: The system cannot locate the resource specified.
at completed (Function code:234:21)
I even tried using the code you posted previously but no luck. This error happens in the dialog that pops up – the friendly message in the dialog says “We cant load that page”
I’ll keep digging through the docs and forums… thanks.
It seems like a network access issue. Are you able to connect to the network from your app? Any way to replicate the problem?