Steps to reproduce:
1.clear deployment cache by executing javaws -uninstall
2.Launch applicaton javaws http://sqeweb.us.oracle.com/deployment1/deployment_6_UR_int_exec_ws/6/deployment/src/javafx/fxfeaturesTest/fxfeaturesTest/html/MissingJarHandleError.jnlp
3.It has a jar file which actually doesn't exist, and the preloader class has overwritten handleErrorNotification, which returns true
4.The error message should be in preloader's panel, no exception should be printed in java console. If exception java.lang.ClassCastException: TestPreloader cannot be cast to javax.jnlp.DownloadServiceListener is printed in java console, and preloader doesn't show, issue is reproduced. (pls see the attached trace file)

The applet work well as expected: http://sqeweb.us.oracle.com/deployment1/deployment_6_UR_int_exec_ws/6/deployment/src/javafx/fxfeaturesTest/fxfeaturesTest/html/MissingJarHandleError.html

source code location: http://sqeweb.us.oracle.com/deployment1/deployment_6_UR_int_exec_ws/6/deployment/src/javafx/fxfeaturesTest/fxfeaturesTest/src/