Reversal can be electrical or mechanical
Openers are designed to react to resistance and safety inputs. Reversal can come from sensor problems, travel or force settings, binding tracks, obstruction, uneven movement, or other mechanical issues.
Watch where the reversal happens
A repeatable reversal at the same point can be a useful clue. Check the visible path for obstruction and sensor condition, but do not adjust springs, cables, or tensioned hardware.
See sensor repair or opener repair depending on the symptom.