BrowserPanicException

During Page reloaded unexpectedly during or after null triggered by beforeunload
    at com.google.jstestdriver.CommandTask.run(CommandTask.java:136)
    at com.google.jstestdriver.JsTestDriverClientImpl.sendCommand(JsTestDriverClientImpl.java:103)
    at com.google.jstestdriver.JsTestDriverClientImpl.runTests(JsTestDriverClientImpl.java:141)
    at com.google.jstestdriver.JsTestDriverClientImpl.runAllTests(JsTestDriverClientImpl.java:120)
    at com.google.jstestdriver.RunTestsAction.run(RunTestsAction.java:69)
    at com.google.jstestdriver.browser.BrowserActionRunner.call(BrowserActionRunner.java:70)
    at com.google.jstestdriver.browser.BrowserActionRunner.call(BrowserActionRunner.java:37)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

    at com.google.jstestdriver.browser.BrowserActionExecutorAction.run(BrowserActionExecutorAction.java:154)
    at com.google.jstestdriver.ActionRunner.runActions(ActionRunner.java:81)
    at com.google.jstestdriver.embedded.JsTestDriverImpl.runConfigurationWithFlags(JsTestDriverImpl.java:342)
    at com.google.jstestdriver.embedded.JsTestDriverImpl.runConfiguration(JsTestDriverImpl.java:233)
    at com.google.jstestdriver.Main.main(Main.java:70)
Caused by:
com.google.jstestdriver.browser.BrowserPanicException: Browser Firefox 30.0 Linux
During Page reloaded unexpectedly during or after null triggered by beforeunload
Unexpected Runner Condition: Failures during test run.