La Liga has confirmed that it did not receive the relevant documents for the agreement by its deadline of midnight on August 31 and Spanish newspaper Marca, known for its close ties with Real Madrid, believes the deal is off until January at the earliest.
Real and United agreed a deal of £29m, a figure which included goalkeeper Keylor Navas going in the opposite direction in exchange for De Gea.
For Manchester United’s part, they have told Sky Sports News HQ that they signed and sent all relevant documentation on time and that they have the evidence to prove it.
As a result, both clubs may consider an appeal over the likely cause of the delay, which may include a computer glitch.
Spanish football expert Guillem Balague told Sky Sports News HQ: “La Liga has confirmed that the documents have not reached them on time and, as it stands, the transfer is not going to take place.
“Everything was done and everyone was waiting. David de Gea was at his girlfriend’s house in Madrid, [Real Madrid president] Florentino Perez was at the Santiago Bernabeu.
“Navas was there too and was waiting to pass a medical, and everything was signed and sent to Manchester.
“But the information is that the documentation didn’t come back from Manchester United on time.
“Reports say the Navas paperwork came in at one minute past midnight in Spain and therefore did not reach La Liga on time, so the transfer is not going to happen.
“There is no precedent for this. Three years ago Fabio Coentrao could not go to Manchester United for the exact same reason, and Real asked the league if they could have five more minutes, and the league said ‘no’.
“Nobody expects an extension, so everyone is reporting that the deal has not gone through.”