Search specifically for a "Full Non-Merged FBNeo Romset" that matches your current version (e.g., v1.0.0.03).
Use a "ROM manager" to scan your old files and update them using a DAT file provided by the FBNeo developers. Step 2: How to Fix Romsets for Free using CLRMamePro
When FBNeo says "unknown," it’s telling you: "I see a zip file here, but the data inside doesn't match the specific version I'm programmed to read." Step 1: Matching Versions (The Golden Rule)
If you have a collection of ROMs that aren't working, you don't necessarily need to download everything again. You can "fix" them using a tool called .