John Mayer was rushed to the hospital on Dec. 5 for an emergency appendectomy in New Orleans.
The singer's rep confirmed the news to TMZ, saying that John is in surgery after being rushed to the E.R. during the early morning hours of Tuesday.
The Dead and Company confirmed the news with a tweet.
"Early this morning, Tuesday, December 5th, John Mayer was admitted into the hospital for emergency appendectomy forcing the Dead & Company December 5th concert in New Orleans to be postponed," the tweet said.
John was in The Big Easy while he tours with The Dead and Company. A show scheduled for Dec. 5 has been postponed. Two other December shows are still scheduled, but they remain in flux.
John has also been touring with his own band.
His tour status is unknown.