When I try to change the range on the DR230 hybrid recorder, error code 123 "Attempted to make settings which are not allowed to be made during saving or reading of measured data" appears.

Check the DR230's main screen to see if RECORD, C, M, or T light up or appear.
If any of them light up or appear, stop those operations.
RECORD: Stop recording.
C: Stop computation. Press the FUNC key, then select MATH STOP.
M or T: Stop saving to memory. Press the SET key, and then select MEMORY > WRITE > STOP > YES.