Q:

webBrowser component throws exception occasionally codenameone

I used WebBrowser component to view the url that occasionally throws following exception and the webBrowser is not displayed if there is an exception. What is the issue here? My code is at the end. thanks
Received exception: Unknown host
java.lang.Throwable: Unknown host
    at javafx.scene.web.WebEngine$LoadWorker.describeError(WebEngine.java:1402)
    at javafx.scene.web.WebEngine$LoadWorker.dispatchLoadEvent(WebEngine.java:1341)
    at javafx.scene.web.WebEngine$LoadWorker.access$1100(WebEngine.java:1219)
    at javafx.scene.web.WebEngine$PageLoadListener.dispatchLoadEvent(WebEngine.java:1206)
    at com.sun.webkit.WebPage.fireLoadEvent(WebPage.java:2387)
    at com.sun.webkit.WebPage.fwkFireLoadEvent(WebPage.java:2231)
    at com.sun.webkit.network.URLLoader.twkDidFail(Native Method)
    at com.sun.webkit.network.URLLoader.notifyDidFail(URLLoader.java:843)
    at com.sun.webkit.network.URLLoader.lambda$didFail$93(URLLoader.java:826)
    at com.sun.webkit.network.URLLoader$$Lambda$168/1472224915.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$164(PlatformImpl.java:292)
    at com.sun.javafx.application.PlatformImpl$$Lambda$64/2085765319.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(PlatformImpl.java:291)
    at com.sun.javafx.application.PlatformImpl$$Lambda$63/817822539.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$141(WinApplication.java:102)
    at com.sun.glass.ui.win.WinApplication$$Lambda$55/1412924864.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)

My code:
InfiniteProgress ip = new InfiniteProgress();
f.addComponent(BorderLayout.NORTH, ip);
WebBrowser view = new WebBrowser() {

    @Override
    public void onStart(String url) {
        System.out.println("del ip");
        f.removeComponent(ip);
    }

};
view.setURL("https://docs.google.com/gview?embedded=true&url=" + pdfUrlSelected);
f.addComponent(BorderLayout.CENTER, view);
f.revalidate();

A:

That generally means your web connection or DNS is problematic.
If the host isn't found networking can't really proceed.

