Here are a few conditions in which trial of labor is absolutely contraindicated:
1. Classical cesarean section. (Vertical incision)
2. Abdominal myomectomy with uterine cavity entry.
Previous cephalopelvic disproportion is not an absolute contraindication for trial of labor (Because if the fetus is small in this pregnancy, a trial of labor can be done.)
Previous low transverse cesarean section (Horizontal incision) is not a contradiction for trial of labor.
These are the ones I found out about. Lemme know if there are more, we'll add them to the list!