Exception in thread "JavaFX Application Thread" java.lang.NoClassDefFoundError: com/sun/javafx/iio/ImageStorage$ImageType
at javafx.graphics/com.sun.javafx.iio.gif.GIFImageLoader2.load(GIFImageLoader2.java:242)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:366)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:274)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:184)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:197)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getImageFrame(WCImageDecoderImpl.java:335)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getFrameCount(WCImageDecoderImpl.java:267)
at javafx.web/com.sun.webkit.network.URLLoader.twkDidFinishLoading(Native Method)
at javafx.web/com.sun.webkit.network.URLLoader.notifyDidFinishLoading(URLLoader.java:868)
at javafx.web/com.sun.webkit.network.URLLoader.lambda$didFinishLoading$5(URLLoader.java:859)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$9(PlatformImpl.java:418)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:417)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)

Exception in thread "JavaFX Application Thread" java.lang.NoClassDefFoundError: com/sun/javafx/iio/ImageStorage$ImageType
at javafx.graphics/com.sun.javafx.iio.gif.GIFImageLoader2.load(GIFImageLoader2.java:242)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:366)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:274)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:184)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:197)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getImageFrame(WCImageDecoderImpl.java:335)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getFrame(WCImageDecoderImpl.java:275)
at javafx.web/com.sun.webkit.WebPage.twkUpdateContent(Native Method)
at javafx.web/com.sun.webkit.WebPage.updateDirty(WebPage.java:306)
at javafx.web/com.sun.webkit.WebPage.updateContent(WebPage.java:633)
at javafx.web/com.sun.javafx.sg.prism.web.NGWebView.update(NGWebView.java:74)
at javafx.web/javafx.scene.web.WebView.handleStagePulse(WebView.java:961)
at javafx.web/javafx.scene.web.WebView.lambda$new$0(WebView.java:267)
at javafx.graphics/com.sun.javafx.tk.Toolkit.lambda$runPulse$2(Toolkit.java:343)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:342)
at javafx.graphics/com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:366)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:518)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:498)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:491)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$11(QuantumToolkit.java:319)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
sizeForDrawing: 680x225 => 0x0 sampling 0
Exception in thread "JavaFX Application Thread" java.lang.NoClassDefFoundError: com/sun/javafx/iio/ImageStorage$ImageType
at javafx.graphics/com.sun.javafx.iio.gif.GIFImageLoader2.load(GIFImageLoader2.java:242)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:366)
at javafx.graphics/com.sun.javafx.iio.ImageStorage.loadAll(ImageStorage.java:274)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:184)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.loadFrames(WCImageDecoderImpl.java:197)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getImageFrame(WCImageDecoderImpl.java:335)
at javafx.web/com.sun.javafx.webkit.prism.WCImageDecoderImpl.getFrame(WCImageDecoderImpl.java:275)
at javafx.web/com.sun.webkit.WebPage.twkUpdateContent(Native Method)
at javafx.web/com.sun.webkit.WebPage.updateDirty(WebPage.java:306)
at javafx.web/com.sun.webkit.WebPage.updateContent(WebPage.java:633)
at javafx.web/com.sun.javafx.sg.prism.web.NGWebView.update(NGWebView.java:74)
at javafx.web/javafx.scene.web.WebView.handleStagePulse(WebView.java:961)
at javafx.web/javafx.scene.web.WebView.lambda$new$0(WebView.java:267)
at javafx.graphics/com.sun.javafx.tk.Toolkit.lambda$runPulse$2(Toolkit.java:343)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:342)
at javafx.graphics/com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:366)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:518)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:498)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:491)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$11(QuantumToolkit.java:319)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)

Load https://www.google.com/logos/doodles/2014/world-cup-2014-27-5917140490125312-hp.gif in HelloWebView, intermittently NoClassDefFoundError error is thrown.