The star, who has matured before the eyes of fans since being cast as Edward Cullen in the Twilight saga, has grown a bit too old to play the role of a young Phineas.
Hollywood Life spoke with Madeline Stowe, the film's director, and this is what she had to say regarding Rob's removal from the role:
"I love Rob so much, but he is a man now! And he was kind of a boy when we first got into this film, so we are on the hunt for a new Phineas right now, that is the piece of casting we are concerned about because Rachel Weisz is a part of the film as well."
Even though Rob won't be taking on this project, fans have no need to worry. The actor is currently filming The Rover in Australia, and has a handful of rumored projects in place, including Maps to the Stars and Mission: Blacklist.