The 18-year-old’s agent Mino Raiola has reportedly asked Milan bosses to cancel the contract on the grounds of “psychological pressure” suffered by Donnarumma to renew last July, Corriere della Sera reported.
Raiola and the player’s lawyers were reportedly not present in the room at the time of the signature.
And the newspaper claims that the teenager — regarded as one of the best young goalkeepers in Europe and a successor to Gianluigi Buffon on the Italian national team — has sent a letter to Milan bosses outlining his demands.
If the agreement is cancelled, Donnarumma would return to his former contract which expires on June 30, 2018, and would be free to join another club.
Paris Saint-Germain are reportedly in talks with Raiola, regarding a transfer to France for the Italian starlet, should Milan fail to clinch Champions League football next season.
Donnarumma brought the long-running saga over his future to an end last July by committing to the San Siro club until 2021 in a deal worth a reported five million euros ($5.8 million) plus bonuses a year.
Former European giants Milan are struggling down in seventh in Serie A — with 21 goals conceded in 16 games — despite Chinese owner Li Yonghong’s 230 million euros summer spending spree.