It was a moment that would go down in Oscars history, for all the wrong reasons.

The movie "La La Land" won the Oscar for best picture -- until it didn't. Presenters Warren Beatty and Faye Dunaway announced the musical, directed by New Jersey's Damien Chazelle, as winner of the evening's most coveted award Sunday night, until people up on stage noticed that the envelope containing the name of the winner read "Moonlight." 

Beatty apologized, saying that he had somehow confused the envelope meant for "La La Land" actress Emma Stone winning best actress for the one intended for best picture. It's not yet clear how Beatty came into possession of the wrong envelope, especially since Emma Stone later said that she had her winning card the whole time.

"I f***ing love 'Moonlight," she said in a press conference after the show, later telling ABC that the other movie's eventual win was "the coolest outcome ever."

@Variety Warren Beatty makes mistake, #Moonlight wins best picture. #Oscars

The mistake was perhaps the largest one ever made in announcing the awards, one host Jimmy Kimmel compared to Steve Harvey's flubbed announcement of the winner of Miss Universe in 2015.

"La La Land" producers, who had already begun to deliver their speeches, quickly ceded the stage to "Moonlight" director Barry Jenkins, who had earlier won an Oscar for best adapted screenplay.

"This is not a joke, 'Moonlight' has won best picture," said "La La Land" producer Jordan Horowitz, holding up the official winner's card so all could see (after a careful closeup).

@JarettSays Watching the #Oscars producers slowly tell the #LaLaLand team they didn't win Best Picture is WILD. Keep your eyes on the background

Chazelle, 32, who grew up in Princeton, earlier became the youngest person to win the Oscar for best director. Near the start of the ceremony, Mahershala Ali became the first Muslim actor to win an Academy Award after he won best supporting actor for his role in "Moonlight." 

"Moonlight" bests "Hidden Figures," "La La Land" (obviously), "Hacksaw Ridge," "Manchester by the Sea," "Lion," "Hell or High Water," "Arrival" and "Fences" to win the coveted award.

On Twitter, where media outlets scrambled to correct or nix their most recent tweets announcing the "La La Land" win, the reaction to the monumental mistake was swift (and yes, Steve Harvey was a running theme).

@WChrisDecker Warren Beatty It's On You Now! #Oscars

@Kounikishi Could someone ask to #pricewaterhousecoopers to audit the next presidential election? Or Warren Beatty perhaps #WhatLaLaHappened #Oscars

@nathanielhaas2 Live look at the stage producer who handed Warren Beatty the wrong envelope #oscars