FoFiX startup errors usually come from the last thing you changed: a theme, a song, or a settings edit. That makes them easier to fix than they look — undo the last change first.
Undo the last change
- If FoFiX broke after a theme change, delete or move that theme folder out of FoFiX’s themes folder and restart.
- If it broke after adding songs, move the newest song folders out of
data\songs\and restart; add them back one at a time. - If settings are the suspect, rename FoFiX’s settings file (back it up first) so the game creates fresh defaults on next launch.
Clean reinstall without losing songs
- Back up your
data\songs\folder and any themes you made. - Install FoFiX into a fresh folder — never over an old vanilla Frets on Fire folder.
- Copy songs back in small batches and restart between batches, so a bad song is easy to identify.
For the install itself, see how to install FoFiX and add themes. If FoFiX runs but a specific song will not load, see songs not showing.
Browse the full hub. Related guides: fofix install themes, frets on fire songs not showing, frets on fire black screen crash.