An unexpected internal exception occured in debug interface layer. Please submit this to your JVM vendor.
Caused: com.sun.jdi.InternalException: Unexpected JDWP Error: 15
   at com.sun.tools.jdi.JDWPException.toJDIException(JDWPException.java:65)
   at com.sun.tools.jdi.ThreadReferenceImpl.currentContendedMonitor(ThreadReferenceImpl.java:490)
   at org.netbeans.modules.debugger.jpda.jdi.ThreadReferenceWrapper.currentContendedMonitor(ThreadReferenceWrapper.java:75)
   at org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl.checkForBlockingThreads(JPDAThreadImpl.java:1868)
   at org.netbeans.modules.debugger.jpda.SingleThreadWatcher.run(SingleThreadWatcher.java:87)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)