The Tony Award-winning actress, 70, called the composer, 71, a “sad sack” in an interview with The New York Times Magazine after Webber reportedly criticized her diction in the musical Evita in his 2018 book, Unmasked: A Memoir.
LuPone played Eva Peron, a role she originated with the 1979 Broadway production and won a Tony Award for. Webber composed the music for the musical with Tim Rice as the lyricist.
“How could he talk about Evita? The whole thing is sung,” LuPone said in response to Webber’s criticism.
She continued, “He’s a jerk. He’s a sad sack. He is the definition of sad sack.”
A rep for Webber did not immediately respond to PEOPLE’s request for comment.
LuPone’s feud with Webber stems all the way to 1994 when the actress was let go from Webber’s Broadway-bound Sunset Boulevard.
The two reportedly reconciled in January 2018, before the publication of Webber’s memoir, after LuPone worked with Webber for a performance of “Don’t Cry for Me Argentina” at the Grammys.
Webber told Playbill at the time he was “delighted” for LuPone’s performance.
“The Grammys suggested it, and I said that if Patti felt she was prepared to do it, I’d be delighted, and she was, and so there we are,” Webber said. “The thing I have to admit I was unprepared for is that Patti’s voice is in incredible shape. I think she’s singing better than when I first knew her.”
He added, “I have to say, Evita is a long time ago now, and none of us are as young as we were, and her voice is like she’s 35. It’s amazing.”