The mass: directory appearing empty in uLaunchELF (uLE) usually occurs because the USB drive is not using the specific file system and partition scheme required by the PlayStation 2. Core Requirements for USB Visibility
ULaunchElf freezes when I access mass when there's a usb in it ulaunchelf mass empty
However, even the most robust tools have their cryptic error messages. One such message that pops up in legacy forums, Reddit threads, and GitHub issue trackers is the phrase "ulaunchelf mass empty" (often appearing as "Mass:" with an empty directory listing, or a specific "empty" error when trying to access USB storage). The mass: directory appearing empty in uLaunchELF (uLE)
Compatibility: Some very large or high-speed USB 3.0/3.1 flash drives are simply incompatible with the older hardware. Try using an older, smaller USB 2.0 drive (e.g., 4GB or 8GB) as a test. Compatibility : Some very large or high-speed USB 3