If you are using the Mac build of the game, please do the following before opening the game:

1.) Navigate to the game.exe file.
2.) Right click the file, and select "Show Info"
3.) Open the "permissions" section
4.) Adjust the settings for it to be able to both write and read files.

Seeing as stupid Apple doesn't trust games not specifically made on and for their platform, your Mac will make the game crash every time you open the game or whenever you save or open the menu. Until RPG Maker MV finds a proper workaround for this, this will have to do. Sorry. ;A;