What the heck is a ".4" file?

[AstralShane5000]

I loaded Yoshi's Island into my Retrode, and the game is actually a ".4" file. What the heck is that file type? I have not heard of that type of ROM before.

[Matthias_H]

It's not a type of rom but a broken config file after firmware update. It's essentially why we recommend the copy-config, flash-firmware, paste-config routine.