Did you add the line below?
Marshal_dump(Heroe_NPC_Name, file)
Heroe_NPC_Name is a class representing a window. I guess you can save an instance of that class but not the class itself. Not like that. Anyway why would you want to save it? I looked at it and it doesn't look like it contains anything that you would want saved.
Also it's Marshal.dump(object, file) not Marshal_dump(object, file).
In any case delete or comment out that line. It's line 1286 inside Complete Faceset & Inn System. I then deleted the save. Played the game and tried to save and it worked. I was also able to load this save.
Good luck with it Calixte9! :thumb: