The season had been due to finish on May 2 and there are nine Championship matches remaining. Barnsley are currently bottom of the table, seven points adrift of safety.
Initially, the campaign was delayed until April 3 due to the outbreak of coronavirus but that has now been increased by four weeks.
The Reds' only game that is not officially postponed is the trip to Brentford on May 2, which was originally due to be their final game.
More in tomorrow's paper.