Minutes before Sam Smith was due to take the stage at Las Vegas' T-Mobile Arena for his set at the iHeartRadio Music Festival, an announcement was heard from the stage.
"Due to unforeseen circumstances which transpired after his rehearsal, it became clear that Sam Smith would unfortunately not be able to perform tonight," said host Ryan Seacrest.
"We love Sam. Sam has been part of our iHeart family for many, many years and we look forward to seeing him really soon."
Smith was scheduled to perform a 25-minute set.
Later, a representative for Smith echoed Seacrest's remarks in a statement to Variety and added, "Sam is extremely sorry he is unable to perform at tonight's show and wants to apologise to his fans."
The rep for the Oscar- and Grammy-winner would not elaborate on the cause of the cancellation.
But according to multiple sources, the nature of the emergency was that Smith inexplicably lost his voice. The British singer had been complaining that his throat was hurting, and given that the performance was airing live across the iHeartRadio network, the decision was made to cancel.
In Smith's place, Childish Gambino went on earlier than scheduled, though the show itself seems to be running about 45 minutes behind.
Smith later left the venue for a chartered flight to Boston.
Australian Associated Press