Sometimes it is possible for createRTTexture to return null which can be later dereferenced by calling rtt.contentsUseful() :

java.lang.NullPointerException: Cannot invoke "com.sun.prism.d3d.D3DRTTexture.contentsUseful()" because "<local6>" is null
at com.sun.prism.d3d.D3DResourceFactory.createPresentable(D3DResourceFactory.java:381)
at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:81)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:358)
at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:122)
at java.base/java.lang.Thread.run(Thread.java:1575)