When loading an url with WebEngine (to get an RSS-feed in my case) I get an exception on a Linux (Debian) box with OpenJDK. See environment for further platform details (Works fine on Windows 7 pro 64bit, with Oracle Jdk 7u2 32bit for example).
webEngine.getDocument() returns null after this.

Exception in thread "JavaFX Application Thread" java.lang.VerifyError: Cannot inherit from final class
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
        at com.sun.webpane.platform.WebPage.twkGetDocument(Native Method)
        at com.sun.webpane.platform.WebPage.getDocument(WebPage.java:1627)
        at javafx.scene.web.WebEngine.updateDocument(WebEngine.java:261)
        at javafx.scene.web.WebEngine.access$1000(WebEngine.java:205)
        at javafx.scene.web.WebEngine$LoadWorker.dispatchLoadEvent(WebEngine.java:901)
        at javafx.scene.web.WebEngine$LoadWorker.access$200(WebEngine.java:765)
        at javafx.scene.web.WebEngine$PageLoadListener.dispatchLoadEvent(WebEngine.java:752)
        at com.sun.webpane.platform.WebPage.fireLoadEvent(WebPage.java:2332)
        at com.sun.webpane.platform.WebPage.fwkFireLoadEvent(WebPage.java:2175)
        at com.sun.webpane.platform.WebPage.twkOpen(Native Method)
        at com.sun.webpane.platform.WebPage.open(WebPage.java:1230)
        at javafx.scene.web.WebEngine.load(WebEngine.java:550)
        at javafx.scene.web.WebEngine.<init>(WebEngine.java:524)
        at javafx.scene.web.WebEngine.<init>(WebEngine.java:506)


Reproducible using the following code
WebEngine webEngine= new WebEngine();
webEngine.load("some_url");