Once you have a working setup, follow these best practices to never see "The DSi binaries are missing" again.

A "trimmed" ROM (to save space) or a ROM hack/randomizer that has stripped or broken these binaries during the modification process. 💡 How to Fix It

The error message typically occurs when using TWiLight Menu++ or nds-bootstrap to run "DSi-enhanced" games (like Pokémon Black/White or Black 2/White 2

Now go forth, clean your ROM collection, and happy gaming.

You might be tempted to search for a "DSi binaries missing fix patch." Do not waste your time. You cannot add back what was never there. All such "fixes" either convert the game to DS mode (disabling DSi features) or corrupt another part of the ROM. The only real fix is to start over with a clean ROM.