The Spain international agreed a six-year deal in principle last month but it remains unsigned.
Jorge Mendes, De Gea's agent, travelled to Manchester this week to finalise the new £350,000-per-week contract.
However, United are still not able to confirm the extension despite everything being in place.
De Gea was linked with a move to PSG at the start of the summer but he now looks set to stay at Old Trafford for the next few seasons.
The former Atletico Madrid man has made 362 appearances for United since joining the club in 2011.
The 8 most momentous opening-day matches in Premier League history
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.