Elton John had to end a concert in Auckland, New Zealand, early on Sunday after losing his voice.
He revealed on Instagram that he had been diagnosed with "walking pneumonia," a less severe form of pneumonia.
"I want to thank everyone who attended tonight's gig in Auckland," he wrote. "I was diagnosed with walking pneumonia earlier today, but I was determined to give you the best show humanly possible. I played and sang my heart out, until my voice could sing no more. I'm disappointed, deeply upset and sorry. I gave it all I had. Thank-you so much for your extraordinary support and all the love you showed me during tonight's performance. I am eternally grateful. Love, Elton."
Video from fans in the audience showed John rising from the piano with outstretched arms and a disappointed look on his face. He briefly appears to shed a few tears before being led off stage.
He warned the audience in advance: "I was diagnosed with walking pneumonia this morning," John said, according to a review from the New Zealand Herald. "My voice is shot but I didn't want to miss this."
Despite his illness, John managed to soldier through nearly two hours of music, performing 15 of a 25-song playlist, according to the Herald's count.
"Walking pneumonia" is a term for pneumonia caused by Mycoplasma pneumoniae, an "atypical" bacteria that often causes mild respiratory infections. Symptoms include tiredness, sore throat, fever and cough, the Centers for Disease Control and Prevention says. Symptoms often appear over one to three weeks and most people recover without antibiotics, according to the U.S. National Library of Medicine.
Nearly three years ago, John had to cancel a run of shows in Las Vegas after contracting a bacterial infection. He spent two nights in intensive care followed by an extended stay in a hospital in April 2017.
John, 72, is in the midst of his three-year farewell tour dubbed "Farewell Yellow Brick Road."
He announced his intention to retire from touring in early 2018, saying he wanted to spend more time with his family.
"It all changed with having children," John told NPR in October. "Ten years ago ... I had nothing planned for the rest of my life except making music and touring, and then we had two fabulous little boys. ... And as much as I love playing, I want to be with my boys now. This is the new part of my life."
Tickets are still available for two more Elton John concerts in New Zealand this week, with no decision yet on whether they will proceed as scheduled.