Charles Ellicott Commentary John 21:1

"After these things Jesus manifested himself again to the disciples at the sea of Tiberias; and he manifested [himself] on this wise." — John 21:1 (ASV)

The impression that St. John would not die belongs to the period when the Second Advent was expected to occur within a lifetime. This period ceased with the first generation of Christians, and this mistake would therefore point to the close of the first century as a limit beyond which the date of the Gospel cannot be placed.