From http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-September/005197.html: ----- Hi all, In NativeDebug.dumpCounters(), there is: out.println("Scope count " + Scope.getCount()); However, Scope doesn't have its own .getCount(), but calls the super (ScriptObject) one. I think Scope.getScopeCount() should be used instead. Thanks, Ahmed -----