DIAGNOSIS Yeah, this one's common. The robot's infrared cliff sensors on the bottom are either dirty or getting a false reading from a very dark floor or a dark area rug.
FIX First, power the robot off. Get a dry cotton swab or a soft cloth and gently wipe the four clear, circular sensors on the underside. Don't use any liquid. Turn it back on and place it on a plain, light-colored floor. Start a cleaning job. If it works, the sensors were just dirty.
IF THAT DIDN'T WORK If it still errors on a dark floor or rug, that surface is likely tripping the safety sensor. The only workaround is to use a physical boundary strip to block the robot from that area. You can't permanently disable the cliff sensors.
HEADS UP If cleaning doesn't fix it and it happens on light floors, one of the sensor LEDs might have failed, which requires contacting Shark support for a repair or replacement.