This is the modern standard for Vita backups. Instead of a single installer file, these are folders containing the original encrypted game files and a fake license. They are generally more stable than VPKs. How to Install PS Vita VPK and UPD Files
Transfer it to your Vita via VitaShell (USB or FTP) and press X to install it. (Note: Using a VPK is perfectly fine for small homebrew apps like PKGj itself). ps vita roms vpk upd
If you own the games and are looking for updates (UPD) or missing files: This is the modern standard for Vita backups
For official retail games backups, updates are usually handled directly through the LiveArea screen by clicking the circular refresh/update arrow above the game icon. How to Install PS Vita VPK and UPD
Requires decryption keys (rif licenses) and a tool like NoNpDRM or NoPayStation to bypass digital rights management (DRM). What is a MaiDump / Vitamin Format?
Download the latest pkgj.vpk from its official GitHub repository.
Follow the same installation steps as above. The Vita will automatically recognize it as an update for the installed title 1.2.3.