Game was scheduled for Tuesday morning but was called off less than an h after Stoke City manager Michael O’Neill was confirmed to have tested positive for Covid-19 after the latest round of testing on Monday.
The planned practice match was cancelled at short notice on Tuesday once the situation became apparent.
Stoke had arrived at United’s Carrington training base and were in the academy building when they found out.
O’Neill, 50, had tested negative in the previous five rounds of testing.
Stoke said the former Northern Ireland boss will now follow the relevant guidance and have a period of isolation.
The Championship club also confirmed on Tuesday that O’Neill will be in regular virtual contact with his coaching staff and players.
Assistant manager Billy McKinlay will take charge of training as the Potters prepare for their game against Reading on June 20.
City sit 17th in the Championship, three points above the relegation zone.