Some developers encrypt their saves. If the editor can't read the file, you may need a tool first to convert it to a readable JSON format. specific decrypter for games that have protected save files?
: A versatile tool that supports older versions including RPG Maker VX, VX Ace, and MV. It requires unpacking on your computer and manually navigating to the save file location to begin editing. rpg maker save editor offline
Most RPG Maker games (MV and MZ) run on JavaScript, making their save files easy to tweak if you have the right software. Some developers encrypt their saves