Barcelona have reportedly made a mistake in Nico Gonzalez's contract with Porto, which allowed the player to join Manchester City from the Portuguese club on Monday.
When Gonzalez first made the move from the Catalan giants, it was stipulated in his contract with Porto that they would keep 40 per cent of the Spaniard's future transfer fee.
Furthermore, the Blaugrana had also secured a buy-back option in Gonzalez's deal in July 2023 for a fixed fee of £25million (€30million).
According to ESPN, the midfielder's move to Manchester City has highlighted the club's error as the Catalans could have triggered the buy-back opportunity to sell the player to Man City for £50.