Archived:Upgrading a MIDlet on Series 40 devices (Known Issue)
In general, you can upgrade a MIDlet already installed on the device by downloading a new version of the MIDlet, which will replace the current version of the MIDlet on the device. On Series 40 phones the MIDlet update process requires that the name and the vendor are the same.
On Series 40 phones you cannot update an existing MIDlet using the JAR file only (without the JAD file). In this case the new MIDlet is installed as a new MIDlet concurrently with the old version.
For an update to succeed, the downloaded MIDlet has to be newer than the version on the phone.
Note also that MIDlets stored on a memory card cannot be updated on Series 40 phones unless the process is started using the "Update Check" menu option.