Syslinux 6.04 _best_ -

SYSLINUX 6.04 is modular: most advanced features are implemented as (32-bit COM-style executables run in protected mode). Important modules include:

Syslinux is a comprehensive suite of lightweight bootloaders designed to start Linux distributions from various media. The suite includes several specialized variants: : For FAT filesystems, commonly used on USB drives. ISOLINUX : For CD/DVD "El Torito" bootable media. syslinux 6.04

This is the most common error. It means the bootloader found the MBR code, but couldn't find the filesystem-specific core file. SYSLINUX 6

Version 6.03, released in 2014, was the last stable, official release of the project. Work on began to address modern requirements like improved EFI (Extensible Firmware Interface) support, which was first introduced in version 6.00. However, development stalled, leaving 6.04-pre1 as the most common iteration found in the wild. ISOLINUX : For CD/DVD "El Torito" bootable media

If you are building a "hybrid" stick that boots on both, you typically install Syslinux for the BIOS path and GRUB for the UEFI path.