Fox has halted production on “Bohemian Rhapsody” due to a “health matter” involving director-producer Bryan Singer.

“Twentieth Century Fox Film has temporarily halted production on ‘Bohemian Rhapsody’ due to the unexpected unavailability of Bryan Singer,” the studio said Friday.

Fox did not elaborate. A representative for the director said that the halt was due to “a personal health matter concerning Bryan and his family. Bryan hopes to get back to work on the film soon after the holidays.”

Filming has been taking place in the U.K. with “Mr. Robot” star Rami Malek in the lead role as Freddie Mercury. New Regency and GK Films are the production companies. The producers are Graham King, Singer, and Jim Beach. Denis O’Sullivan, Arnon Milchan, and Jane Rosenthal are the executive producers.

Singer reportedly also had unexplained absences during the productions of “Superman Returns” and “X-Men: Apocalypse.”

Singer, who is 52, has directed films including “The Usual Suspects,” four X-Men movies including last year’s “X-Men: Apocalypse,” “Jack the Giant Slayer” and “Superman Returns.”

Ben Hardy is playing drummer Roger Taylor. Gwilym Lee (“The Hollow Crown”) will portray lead guitarist Brian May and Joe Mazzello (“The Social Network”) will tackle the role of bass guitarist John Deacon. Lucy Boynton is playing Mary Austin, lifelong companion of Mercury.

Mercury wrote numerous hits for Queen, including “Bohemian Rhapsody,” “Killer Queen,” “Somebody to Love,” “Don’t Stop Me Now,” “Crazy Little Thing Called Love,” and “We Are the Champions.”

Mercury formed Queen with May and Taylor in 1970 and died of complications from HIV/AIDS in 1991 at the age of 45.

Justin Haythe wrote the script. The film is slated for U.S. release on Dec. 25, 2018.