OpenLaszlo 4.2 is the recommended platform for all application development in the SWF8, SWF9, and DHTML runtimes. The major new feature in OpenLaszlo 4.2 is the introduction of the SWF9 runtime, which can offer significant performance gains. Unlike previous versions of the Flash player, SWF9 has much stronger typing requirements and you must modify your code to take advantage of the performance gains it offers. To assist you in upgrading your applications to OpenLaszlo 4.2, we have provided various conversion scripts depending on your application goals.

To migrate your 4.0.X or 4.1.1 applications, we strongly suggest that you refer to this wiki page: Runtime_Differences. This page discusses the changes required by SWF9 and also provides a methodology for upgrading your application. It is very important that you run the automated conversion scripts in the recommended order