Before you start dragging files onto a USB drive, you must understand the distinct roles of these two file types.
The file is the delivery vehicle for PS3 software. It acts as a digital container—similar to an .exe or .msi on Windows—that holds the game data, updates, or DLC in a compressed format. pkg rap ps3
This means the RAP file is missing or wasn't placed in the exdata folder. Before you start dragging files onto a USB
If you legally own a digital PS3 game, backing up its PKG and generating your own RAP file (using tools on your own console) for personal archival use may fall under fair use or backup exceptions in some regions—though this is legally complex and varies by country. pkg rap ps3