Back in the day, ROM dumps often included a 512-byte or 1024-byte header added by dumping hardware. Modern emulators like FBNeo expect . If your ROM still contains that header, the CRC32 checksum will be wrong, and FBNeo will reject it.
He smiled, picked up his controller, and hit the gas. fbneo romset unknown
Many users rely on curated collections like "FBNeo Romset Complete (Rollback)." These sets are updated sporadically. If you have Rollback set 1.0.0, but you updated FBNeo to version 1.0.3, you will get "unknown" for any game that had a ROM update between those two releases. Back in the day, ROM dumps often included