Chef Selenium: Strange error when I go to the hub ip:4444/wd/hub

Question

I get the following stacktrace:

{
    "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": 237
            },
            {
                "fileName": "RequestHandler.java",
                "className": "org.openqa.grid.web.servlet.handler.RequestHandler",
                "methodName": "process",
                "lineNumber": 119
            },
            {
                "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": 707
            },
            {
                "fileName": "HttpServlet.java",
                "className": "javax.servlet.http.HttpServlet",
                "methodName": "service",
                "lineNumber": 820
            },
            {
                "fileName": "ServletHolder.java",
                "className": "org.seleniumhq.jetty7.servlet.ServletHolder",
                "methodName": "handle",
                "lineNumber": 565
            },
            {
                "fileName": "ServletHandler.java",
                "className": "org.seleniumhq.jetty7.servlet.ServletHandler",
                "methodName": "doHandle",
                "lineNumber": 479
            },
            {
                "fileName": "SessionHandler.java",
                "className": "org.seleniumhq.jetty7.server.session.SessionHandler",
                "methodName": "doHandle",
                "lineNumber": 225
            },
            {
                "fileName": "ContextHandler.java",
                "className": "org.seleniumhq.jetty7.server.handler.ContextHandler",
                "methodName": "doHandle",
                "lineNumber": 1031
            },
            {
                "fileName": "ServletHandler.java",
                "className": "org.seleniumhq.jetty7.servlet.ServletHandler",
                "methodName": "doScope",
                "lineNumber": 406
            },
            {
                "fileName": "SessionHandler.java",
                "className": "org.seleniumhq.jetty7.server.session.SessionHandler",
                "methodName": "doScope",
                "lineNumber": 186
            },
            {
                "fileName": "ContextHandler.java",
                "className": "org.seleniumhq.jetty7.server.handler.ContextHandler",
                "methodName": "doScope",
                "lineNumber": 965
            },
            {
                "fileName": "ScopedHandler.java",
                "className": "org.seleniumhq.jetty7.server.handler.ScopedHandler",
                "methodName": "handle",
                "lineNumber": 117
            },
            {
                "fileName": "HandlerWrapper.java",
                "className": "org.seleniumhq.jetty7.server.handler.HandlerWrapper",
                "methodName": "handle",
                "lineNumber": 111
            },
            {
                "fileName": "Server.java",
                "className": "org.seleniumhq.jetty7.server.Server",
                "methodName": "handle",
                "lineNumber": 349
            },
            {
                "fileName": "AbstractHttpConnection.java",
                "className": "org.seleniumhq.jetty7.server.AbstractHttpConnection",
                "methodName": "handleRequest",
                "lineNumber": 452
            },
            {
                "fileName": "BlockingHttpConnection.java",
                "className": "org.seleniumhq.jetty7.server.BlockingHttpConnection",
                "methodName": "handleRequest",
                "lineNumber": 47
            },
            {
                "fileName": "AbstractHttpConnection.java",
                "className": "org.seleniumhq.jetty7.server.AbstractHttpConnection",
                "methodName": "headerComplete",
                "lineNumber": 884
            },
            {
                "fileName": "AbstractHttpConnection.java",
                "className": "org.seleniumhq.jetty7.server.AbstractHttpConnection$RequestHandler",
                "methodName": "headerComplete",
                "lineNumber": 938
            },
            {
                "fileName": "HttpParser.java",
                "className": "org.seleniumhq.jetty7.http.HttpParser",
                "methodName": "parseNext",
                "lineNumber": 634
            },
            {
                "fileName": "HttpParser.java",
                "className": "org.seleniumhq.jetty7.http.HttpParser",
                "methodName": "parseAvailable",
                "lineNumber": 230
            },
            {
                "fileName": "BlockingHttpConnection.java",
                "className": "org.seleniumhq.jetty7.server.BlockingHttpConnection",
                "methodName": "handle",
                "lineNumber": 66
            },
            {
                "fileName": "SocketConnector.java",
                "className": "org.seleniumhq.jetty7.server.bio.SocketConnector$ConnectorEndPoint",
                "methodName": "run",
                "lineNumber": 254
            },
            {
                "fileName": "QueuedThreadPool.java",
                "className": "org.seleniumhq.jetty7.util.thread.QueuedThreadPool",
                "methodName": "runJob",
                "lineNumber": 599
            },
            {
                "fileName": "QueuedThreadPool.java",
                "className": "org.seleniumhq.jetty7.util.thread.QueuedThreadPool$3",
                "methodName": "run",
                "lineNumber": 534
            },
            {
                "fileName": "Thread.java",
                "className": "java.lang.Thread",
                "methodName": "run",
                "lineNumber": 745
            }
        ]
    }
}

Have you seen such errors?

Do you have any idea how to solve this because there is nothing in the log files?

Answer 1

After doing some research, it seems like this is expected behavior and shouldn't impact testing:

https://github.com/nicegraham/selenium-grid2-api/blob/master/README.md#wdhub