Nikon Z9 Mirrorless Camera - Manual (Page 747)

747 B The Setup Menu: Camera Setup
Choose whether the shutter can be released when no memory card is
inserted in the camera.
Slot Empty Release Lock
G button
U B setup menu
Option Description
a
[ Release
locked ]
The shutter cannot be released when no memory
card is inserted.
b
[ Enable
release ]
The shutter can be released with no memory card
inserted. No pictures will be recorded; during
playback, the camera displays [
Demo ].