Possibly one of the best texts that prove that infallibility of the Popes is false, is the letter of Pope Adrian I, Greek translation of which was read on the Seventh Ecumenical Council:
I mean fragment about primacy of the Pope from the last line of p. 48 until the sign of the cross on p. 49. This is English translation from Greek translation of the letter. And in footnotes of p. 49 there is English translation of Latin original of this fragment. Doesn't this show, that Greeks simply didn't know about infallibility of the Popes? Because if they knew, then they wouldn't had deleted this teaching in their translation by replacing "the blessed Peter, Prince of the Apostles" with "Apostles SS. Peter and Paul".
English translation from Greek translation of the letter of Pope Adrian I:
"And, more especially, if ye follow the traditions of the orthodox faith of those chief Apostles SS. Peter and Paul, and kindly welcome their Vicar, even as your predecessors honoured each one the Vicar of his own days. And let your divinely-received power give all honour to the most holy Roman Church of these chief Apostles, to whom power has been granted by God, the Word Himself, to loose and to bind sins in heaven and on earth; for they will become the guardians of your kingdom, and will subdue all the barbarous nations under your feet, and wherever ye go they will make you victorious. Now these same
holy and chief Apostles, who laid the foundation of the Catholic and Orthodox faith, have left a written law, that all who ever should succeed to their thrones should maintain the same faith, and should continue in it even unto the end, and thus it is that our Church maintains and honours holy images."
In the Latin the name of Peter stands alone. In the Latin this paragraph runs as follows --
“For the proofs of his dignity are found in the sacred authors, and in that unbounded veneration paid to him by all the faithful everywhere throughout the world, for the Lord hath made Him who is keeper of the keys of heaven, Prince over all; and this privilege was conferred upon Him by the same Divine Person by whom the keys of the kingdom of heaven were granted; for He that was endued with such singular honour, had before been honoured to make that confession of faith on which the Church of Christ is founded. A blessedness of reward followed this blessed confession, by preaching of which the holy Catholic Church has been enlightened, and from which other Churches have taken the documents of their faith; for the blessed Peter, Prince of the Apostles, who first presided in the Apostolic See, bequeathed the Principality of the Apostleship and the pastoral care to his successors who, throughout all ages, should sit in his most holy chair, to whom he left the power of authority; for just as it was bestowed on him by our Lord and Saviour Jesus Christ, so in the same way did he hand it down by divine command to the Pontiffs, his successors, by whose tradition it is that we venerate the holy images of Christ, of His holy Mother, of the Apostles, and all Saints.”