More specifically: How does the Roman Catholic Church reconcile the doctrine of Papal Infallibility with the Sixth Ecumenical Council's pronouncement regarding Pope Honorius?
The Sixth Ecumenical Council (680-681 CE) posthumously declared Pope Honorius to be a heretic because he had embraced the doctrine of monothelitism.
The doctrine of Papal Infallibility, formalized in 1870 but said to have been an accepted teaching for many centuries, says that when the Bishop of Rome speaks "ex cathedra" he is necessarily infallible.
Even if Pope Honorius did not speak ex cathedra when discussing monothelitism, it seems problematic that the same church which declared an individual capable of infallible speech could later find that the same individual was also a heretic.
Has the Roman Catholic Church ever formally addressed this seeming tension, and if so, where and how?