Stone, who won the Best Actress award at the gala on February 26, was still celebrating her win when Warren Beatty and Faye Dunaway announced that 'La La Land' won the Best Picture category. Shortly after the cast walked onto the stage to accept the trophy, panicked Oscars team announced that there was a mistake as the winner was supposed to be 'Moonlight'.
"(It was) One of the most horrible moments of my life. Wow! It was just so horrible," Stone said.
PricewaterhouseCoopers, the company which was responsible for the Academy voting, has apologised for the mistake.
"We sincerely apologise to 'Moonlight', 'La La Land', Warren Beatty, Faye Dunaway and Oscar viewers for the error that was made during the award announcement for Best Picture," said Brian Cullinan, a representative for the firm.