The film was set to hit cinemas on 24 May after a Cannes Film Festival debut, but reports suggest it's some way from being complete.
Director James Gray has always maintained a Memorial Day weekend release was ambitious, and now it looks as it the movie will be released in the autumn.
In the film, Pitt plays and astronaut searching for his missing father.
Hours after the news Pitt's film had been pushed back broke, it was announced his ex-wife Angelina Jolie's next project is ready to roll.
She'll star in writer/director Taylor Sheridan's thriller "Those Who Wish Me Dead", which is set to start principal photography later this month.
"Taylor Sheridan is an exceptional filmmaker, and we are thrilled to be partnering with him, Angelina Jolie... and the entire filmmaking team on this exciting project," New Line producers Carolyn Blackwood and Richard Brener said in a joint statement.