Nikon Z8 User Manual page 831

Slot Empty Release Lock
Choose whether the shutter can be released when no memory card is inserted in the camera.
Option
[Release locked]
a
[Enable release]
b
The shutter cannot be released when no memory card is inserted.
The shutter can be released with no memory card inserted. No pictures
will be recorded; during playback, the camera displays [Demo].
Description
757
G button U B setup menu
Slot Empty Release Lock