Quote taken from shoutout
If you get certificate error when attempting to install the program or themes on your S60 3rd Edition smartphone, it means that you haven enabled installation of unsigned SIS files. Go to Tools -> App. Manager, choose Options -> Settings and set Software installation to All and Online certif. check to Off.
If you get certificate error when attempting to install the program or themes on your S60 3rd Edition smartphone, it means that you haven enabled installation of unsigned SIS files. Go to Tools -> App. Manager, choose Options -> Settings and set Software installation to All and Online certif. check to Off.