I sometimes get NPEs from WebHistory:
     [java] Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
     [java] at javafx.scene.web.WebHistory$Entry$1.stateChanged(WebHistory.java:68)
     [java] at com.sun.webpane.platform.BackForwardList$Entry.notifyItemChanged(BackForwardList.java:64)
     [java] at com.sun.webpane.webkit.network.URLLoader.twkDidReceiveData(Native Method)
     [java] at com.sun.webpane.webkit.network.URLLoader.access$1200(URLLoader.java:42)
     [java] at com.sun.webpane.webkit.network.URLLoader$5.run(URLLoader.java:640)
     [java] at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:76)

E.g. try loading this URL into WebLauncher:
     http://content.rbc.medialand.ru/autonews.ru//?http%3A//engine.rbc.medialand.ru/reference%3Fgid%3D2%26pid%3D920%26bid%3D38484%26rid%3D258347971