Manchester United and Villarreal were initially paired with each other, having also met in the group stages.
Teams from the same country and team who were in the same group are not permitted to meet at this stage of the competition. Group winners cannot also face each other at this point.
The Red Devils were then paired with Paris Saint Germain while Villarreal got a date with Manchester City.
The draw will therefore be conducted again by UEFA as per a statement they have released.
The statement reads: 'Following a technical problem with the software of an external service provider that instructs the officials as to which teams are eligible to play each other, a material error occurred in the draw for the UEFA Champions League Round of 16.
'As a result of this, the draw has been declared void and will be entirely redone at 15.00 CET today, Monday 13 December 2021.'
