"I want to thank everyone who attended tonight’s gig in Auckland," John wrote on Instagram. "I was diagnosed with walking pneumonia earlier today, but I was determined to give you the best show humanly possible."
John, 72, was playing Mount Smart Stadium in Auckland, as part of his "Farewell Yellow Brick Road" tour, when he ended the performance after approximately two hours, according to Billboard.
Videos posted to social media show John visibly upset as he ends the show and is escorted off stage.
"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," John wrote on Instagram.
"Walking pneumonia" is the common term for a mild case of pneumonia with flu-like symptoms, according to the American Lung Association.
A week prior to announcing his pneumonia diagnosis, John and longtime collaborator Bernie Taupin won an Oscar at the 92nd Academy Awards for best original song "(I'm Gonna) Love Me Again" from the biographical "Rocketman."