He will be the fourth goalkeeper at City manager Pep Guardiola’s disposal, with Ederson, Stefan Ortega and Marcus Bettinelli already at the club.
It is anticipated Trafford will challenge Brazil international Ederson, who has been first-choice goalkeeper for eight years, for the number one spot.
Ederson is in the final year of his contract and has been linked with a move to Galatasaray but City haven’t received any bids for him yet, while there are doubts about German Ortega.
Trafford signed for City’s academy in 2015 but never made a first-team appearance and spent time on loan at Accrington Stanley and Bolton Wanderers.
Trafford is expected to sign a five-year contract at Etihad Stadium with the option for another year.
More to follow.
