The Star Wars actor had cleared his schedule to take on the screen adaptation of Jonathan Franzen's bestselling novel The Corrections, about the family troubles of an elderly couple and its three adult children, portrayed by McGregor, Bruce Norris and Maggie Gyllenhaal.
However, bosses at America's HBO network were not impressed with the pilot episode, directed by Noah Baumbach, and the project was scrapped in May (12).
Now McGregor admits the failed venture was a huge disappointment for him.
He tells New York Magazine, "At first I was sad, but when I saw the pilot I was devastated. Creatively, I was destroyed because it was so powerful."
The actor had made a conscious decision not to sign up for big film roles after he agreed to take on a role in The Corrections because he was convinced the series was good enough to run for four or five years.
But as a result of its cancellation, McGregor has been left with weeks of downtime in between projects.
He says, "This is the least work I've ever done in my life, since I was 20 or 21, because of HBO and The Corrections."