On the death of Zachary, a certain priest Stephen was unanimously elected to succeed him (about 23 March, 752); but on the third day after his election, whilst transacting some domestic affairs, he was struck with apoplexy, and expired on the next day. As he died before his consecration, earlier writers do not appear to have included him in the list of the popes; but, in accordance with the long standing practice of the Roman Church, he is now generally counted among them. This divergent practice has introduced confusion into the way of counting the Popes Stephen.
Ed. Duchesne, Liber Pontificalis, I (Paris, 1886), 440, MANN, Lives of the Popes, I, pt. ii (London, 1902), 290 sq.