Most people encounter this issue while using the . RetroArch is particularly sensitive to ROM versions.
This sounds basic, but it is a common culprit. romset is unknown fbneo fixed
Use a manager to ensure your files aren't corrupted or old dumps. Most people encounter this issue while using the
FBNeo will read the Parent files first, then overlay the Clone files. The "unknown" error will vanish. romset is unknown fbneo fixed
Arcade games often had multiple versions: USA, Japan, Europe, Bootleg, Revision 1, Revision 2, etc.