DIAGNOSIS The force settings are too sensitive, or the safety sensors are slightly misaligned. The opener thinks it's hitting an obstruction when it's not.
FIX Start with the sensors. 1) Check the small LED lights on both sensor units. They should both be solid, not blinking. 2) If one is blinking or off, clean the lenses with a soft cloth and adjust their alignment until both LEDs are solid. 3) If the sensors are fine, adjust the force. On your wall control, hold the door button until the light flashes. Then press it once to increase closing force, or twice to decrease it. Test the door. It should close and stop gently on the floor.
IF THAT DIDN'T WORK The door itself might be the issue. A stiff roller, a binding track, or a broken spring can increase the force needed to move the door. Manually operate the door. It should lift smoothly with one hand. If it's heavy or jerky, the opener is fighting the problem—call a door technician.
HEADS UP When adjusting force, make sure the auto-reverse feature still works. Place a 2x4 piece of wood on the floor where the door closes. The door must reverse when it hits the wood. If it doesn't, your force settings are too high and it's unsafe.