Java – selenium: http: / / localhost: 4444 / WD / hub returns NullPointerException. What did I do wrong

Given: try using this code to use remotewebdriver in c#

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

The new remotewebdriver code above will not respond until it times out

More details

I have started my hub to selenium server with these parameters:

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

And registered a node with 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 enter this URL after starting the hub, it indicates that there are registered nodes:

http://location:4444/grid/console

However, when you enter this URL after starting hub

http://localhost:4444/wd/hub

The browser display points to externalsessionkey This Java (JSON) stack trace for 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},"methodName":"process","lineNumber":118},{"fileName":"DriverServlet.java","className":"org.openqa.grid.web.servlet.DriverServlet","lineNumber":83},"methodName":"doGet","lineNumber":61},{"fileName":"HttpServlet.java","className":"javax.servlet.http.HttpServlet","methodName":"service","lineNumber":687},"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","lineNumber":221},{"fileName":"ContextHandler.java","className":"org.seleniumhq.jetty9.server.handler.ContextHandler","lineNumber":1127},"methodName":"doScope","lineNumber":515},"lineNumber":185},"lineNumber":1061},{"fileName":"ScopedHandler.java","className":"org.seleniumhq.jetty9.server.handler.ScopedHandler","lineNumber":141},{"fileName":"HandlerWrapper.java","className":"org.seleniumhq.jetty9.server.handler.HandlerWrapper","lineNumber":97},{"fileName":"Server.java","className":"org.seleniumhq.jetty9.server.Server","lineNumber":499},{"fileName":"HttpChannel.java","className":"org.seleniumhq.jetty9.server.HttpChannel","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},"className":"org.seleniumhq.jetty9.util.thread.QueuedThreadPool$3","lineNumber":555},{"className":"java.lang.Thread","lineNumber":-1}]}}

Anyone can explain stack trace to me and how to make it work?

thank you!

Solution

There's nothing wrong with your ending

The URL http: / / localhost: 4444 / WD / hub is designed so that it expects payload to work with you Since you did not provide the required payload, you will see a NullPointerException

This URL should not be opened in a browser It means that the appropriate payload is consumed through HTTP operation, which complies with selenium W3C spec