No Lens Attached: Fujifilm GFX CamerasUpdated a year ago

The camera needs to be set to function without a GFX-Mount lens attached. You can do this by changing the following camera setting:

    ‘MENU’ -> ‘SETUP’ -> ‘BUTTON/DIAL SETTING’ -> ‘SHOOT WITHOUT LENS’ -> ‘ON’

        (Exact naming and location of this option may change depending on camera model)

    Choose ON to enable the shutter release when no lens is attached.

http://fujifilm-dsc.com/en/manual/gfx50s/menu_setup/button-dial_setting/index.html#shoot_without_lens