Details aren't clear, but Ryan Seacrest announced during our iHeartRadio Music Festival broadcast that Sam Smith would be unable to perform. Sam addressed the situation and released a statement via Twitter:
Dear all, Due to unforeseen circumstances which transpired after rehearsal, it became clear that I’m sadly unable to perform at the iHeart Radio Music Festival in Vegas tonight. I am so so sorry about this and I want to apologise to all my fans. All my love, always. Sam x— Sam Smith (@samsmith) September 22, 2018
We will, of course, bring you more information if we receive it.