To truly turn a Java app into a VXP, you must port the source code using the MediaTek MRE SDK Install the

Without this wrapper, most MediaTek-powered phones (MT6260, MT6261, etc.) will simply display “Invalid Application” when you try to run a raw .jar file.

Sometimes, a converted .VXP file won't run on certain devices (like the Nokia 225) because of security restrictions or missing IMSI identifiers.

Tools like Jadx can help you view the original Java source code if you plan on manually porting the app. Important Considerations Convert Java To Vxp - Google Groups

The direct conversion might require: