Selenium: http://localhost:4444/wd/hub returns a NullPointerException, what am I doing incorrectly

Question

Given: Attempting to use a RemoteWebDriver in C# with this code.

var url = new Uri("http://localhost:4444/wd/hub");
var wd = new RemoteWebDriver(url, DesiredCapabilities.Chrome());

The new RemoteWebDriver code above doesn't respond until there's a timeout...

More Details

I've started my Hub with these parameters to the Selenium Server:

-jar "C:\SomeFolder\selenium-server-standalone-3.0.1.jar" -port 4444 -role hub

And registered a Node using these parms..

-jar "C:\SomeFolder\selenium-server-standalone-3.0.1.jar" -role node -hub http://localhost:4444/grid/register -port 9662 

Debugging

If I type in this URL after starting the Hub, It shows there is a registered Node:

http://location:4444/grid/console

But when typing in this url after starting the Hub

http://localhost:4444/wd/hub

The browser shows this java (json) stack trace pointing to ExternalSessionKey.java

{"status":13,"value":{"class":"java.lang.NullPointerException","stackTrace":[{"fileName":"ExternalSessionKey.java","className":"org.openqa.grid.internal.ExternalSessionKey","methodName":"fromWebDriverRequest","lineNumber":77},{"fileName":"WebDriverRequest.java","className":"org.openqa.grid.web.servlet.handler.WebDriverRequest","methodName":"extractSession","lineNumber":62},{"fileName":"RequestHandler.java","className":"org.openqa.grid.web.servlet.handler.RequestHandler","methodName":"getSession","lineNumber":231},{"fileName":"RequestHandler.java","className":"org.openqa.grid.web.servlet.handler.RequestHandler","methodName":"process","lineNumber":118},{"fileName":"DriverServlet.java","className":"org.openqa.grid.web.servlet.DriverServlet","methodName":"process","lineNumber":83},{"fileName":"DriverServlet.java","className":"org.openqa.grid.web.servlet.DriverServlet","methodName":"doGet","lineNumber":61},{"fileName":"HttpServlet.java","className":"javax.servlet.http.HttpServlet","methodName":"service","lineNumber":687},{"fileName":"HttpServlet.java","className":"javax.servlet.http.HttpServlet","methodName":"service","lineNumber":790},{"fileName":"ServletHolder.java","className":"org.seleniumhq.jetty9.servlet.ServletHolder","methodName":"handle","lineNumber":808},{"fileName":"ServletHandler.java","className":"org.seleniumhq.jetty9.servlet.ServletHandler","methodName":"doHandle","lineNumber":587},{"fileName":"SessionHandler.java","className":"org.seleniumhq.jetty9.server.session.SessionHandler","methodName":"doHandle","lineNumber":221},{"fileName":"ContextHandler.java","className":"org.seleniumhq.jetty9.server.handler.ContextHandler","methodName":"doHandle","lineNumber":1127},{"fileName":"ServletHandler.java","className":"org.seleniumhq.jetty9.servlet.ServletHandler","methodName":"doScope","lineNumber":515},{"fileName":"SessionHandler.java","className":"org.seleniumhq.jetty9.server.session.SessionHandler","methodName":"doScope","lineNumber":185},{"fileName":"ContextHandler.java","className":"org.seleniumhq.jetty9.server.handler.ContextHandler","methodName":"doScope","lineNumber":1061},{"fileName":"ScopedHandler.java","className":"org.seleniumhq.jetty9.server.handler.ScopedHandler","methodName":"handle","lineNumber":141},{"fileName":"HandlerWrapper.java","className":"org.seleniumhq.jetty9.server.handler.HandlerWrapper","methodName":"handle","lineNumber":97},{"fileName":"Server.java","className":"org.seleniumhq.jetty9.server.Server","methodName":"handle","lineNumber":499},{"fileName":"HttpChannel.java","className":"org.seleniumhq.jetty9.server.HttpChannel","methodName":"handle","lineNumber":310},{"fileName":"HttpConnection.java","className":"org.seleniumhq.jetty9.server.HttpConnection","methodName":"onFillable","lineNumber":257},{"fileName":"AbstractConnection.java","className":"org.seleniumhq.jetty9.io.AbstractConnection$2","methodName":"run","lineNumber":540},{"fileName":"QueuedThreadPool.java","className":"org.seleniumhq.jetty9.util.thread.QueuedThreadPool","methodName":"runJob","lineNumber":635},{"fileName":"QueuedThreadPool.java","className":"org.seleniumhq.jetty9.util.thread.QueuedThreadPool$3","methodName":"run","lineNumber":555},{"className":"java.lang.Thread","methodName":"run","lineNumber":-1}]}}

Can anyone interpret the Stack Trace for me, and what to do to get this working?

Thanks!

Answer 1

There is nothing wrong at your end.

The URL http://localhost:4444/wd/hub is designed such that it expects a PAYLOAD with your operation. Since you haven't provided the desired payload you are seeing a NullPointerException.

This URL is not supposed to be opened up in a browser. Its meant to be consumed via Http operations with a proper payload that adheres to the Selenium w3c spec