This is a bad sensor. Sublime Master Reginald explains and provides the part link:

F30 ERR

If the EOC detects that the oven temperature probe circuit is OPEN during the initial power up

you will not be able to program the time of day and the EOC will display “F30 ERR”

and the alarm will sound when you attempt to set the time.

click on picture

Source: Frigidaire oven F30 error code