Harvey, who incorrectly announced the winner of the Miss Universe contest in 2015, had a sense of humor when he tweeted his support for Beatty on Monday morning.
"Call me Warren Beatty. I can help you get through this! #Oscars," he wrote.
In the final award of the evening on Sunday, La La Land was announced as the Best Picture winner, even though it did not win the award. After the show, PricewaterhouseCoopers explained that the presenters had mistakenly been given the wrong category envelope.
After the La La Land team had started accepting the award, producer Jordan Horowitz stepped forward to show the correct envelope and reveal that Moonlight was the true winner.
Shortly after the show, social media users poked fun at "envelope-gate," including the Miss Universe Twitter page.