Why does my garage door keep reversing when I close it?

Your garage door keeps reversing when you close it because its safety system detects obstruction, misalignment, or excessive force that triggers auto reverse to prevent injury, which is required safety feature. Most common cause is misaligned or dirty safety sensors near floor; sensors must face each other with steady yellow on sender and steady green on receiver, and if green blinks or is off due to dirt, spider webs, bumped bracket, or sunlight interference, beam breaks and door reverses and opener lights flash 10 times. Clean lenses and realign sensors. Second cause is close force setting too sensitive on opener motor unit; if tracks are dirty, rollers lack lubrication, or springs weak making door heavy, opener feels resistance and reverses thinking there is obstruction. Increase close force slightly per manual, one quarter turn, and lubricate rollers with silicone lubricant twice yearly. Travel limits set incorrectly causing door to hit floor too hard and bounce back also causes reversal; adjust down limit so door touches floor without excessive pressure. Weak springs that no longer counterbalance door weight make door heavy and trigger reversal. Obstruction in tracks, bent track, or damaged roller causes binding. To diagnose, disconnect opener via emergency release cord and manually close door; if it moves smoothly, issue is sensors or force settings, if it binds, fix tracks. Professional adjustment costs 75 to 150 dollars. Keep gutters clean to prevent water damage rusting tracks that cause binding.