Yet close to the Vatican's synod hall, about two dozen abuse survivors staged a sit-in, demanding their cause be taken up at the meeting and voicing outrage that some of the delegates had covered up for abusive priests.
"Make 'Zero Tolerance' Real," read one protest sign.
Francis welcomed more than 250 priests, bishops and cardinals, as well as 34 young Catholics, to a month-long meeting on ministering to future generations, urging young and old to listen to one another without prejudice.
He prayed for God's help to ensure the church "does not allow itself, from one generation to the next, to be extinguished or crushed by the prophets of doom and misfortune, by our own shortcomings, mistakes and sins".
The October 3-28 synod comes amid new revelations about decades of sexual misconduct by priests and cover-ups in the US, Chile, Germany and elsewhere.
It has been a disastrous year for the pope on the abuse front, after he botched a prominent cover-up scandal in Chile before changing course.
More recently, he has been accused of rehabilitating an American ex-cardinal who pressured seminarians to sleep with him.
Those cases, coupled with the release of devastating studies about decades of abuses and cover-ups in Pennsylvania and Germany that predated his papacy, have fuelled doubts about his oft-stated pledge of having "zero tolerance" for that, since implicated bishops remain in place.
"Pope Francis talks about 'zero tolerance,' and that bishops who cover-up should be removed and put on trial," said Alessandro Battaglia, who was 15 when he was abused by a Milan-area priest who last month was convicted and sentenced to over six years in prison.
The current archbishop of Milan, Mario Delpini, gave evidence at the trial of Mauro Galli that he had transferred Galli to another parish rather than report him to police or keep him away from other potential victims, as Mr Battaglia's family had requested.
Despite publicity about the case, Francis named Mr Delpini archbishop of Milan in July and named him a papal delegate at the synod.
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