Comic book fans will have to wait a little bit longer to see the Flash race into theaters, and Albus Dumbledore may be partly to blame for the delay.

Warner Bros. is pushing back the start of filming on the studio’s still untitled standalone Flash film, sources tell Variety. The film never received a formal greenlight nor did it have a set release date, but it had been expected to begin shooting in March. However, a script is still being tweaked and the studio thinks that it won’t have enough time to get the script in shape in order for the film to make its original start date.

That’s a problem, because Ezra Miller, the live-wire performer tasked with playing the Flash, also has a key supporting role in “Fantastic Beasts,” the “Harry Potter” spin-off series. The third film in the franchise begins shooting in July, which would cause scheduling headaches. The standalone Flash film is now expected to commence production in late 2019. That likely means the superhero adventure won’t debut in theaters until some time in 2021.

The Flash movie has had a long gestation. Last January, Warner Bros. signed “Spider-Man: Homecoming” scribes John Francis Daley and Jonathan Goldstein to direct the film. They replaced “Dope” director Rick Famuyiwa, who left the film in 2016 over creative differences. His exit put the picture in limbo until a new filmmaker could be found.

Following the box office disappointment of “Justice League,” Warner Bros. has been reevaluating its approach to making movies based on DC Comics characters. The studio is not currently moving forward with Batman and Superman movies featuring Ben Affleck and Henry Cavill, respectively. It is expected to recast the Dark Knight with a different actor for director Matt Reeves’ upcoming Batman solo outing. The studio will be fielding a number of superhero adventures in the coming months and years. It is releasing “Aquaman” this December, and next year will bring a “Wonder Woman” sequel. The studio also has a “Suicide Squad” follow-up and a Joker movie with Joaquin Phoenix waiting on deck.