YOU HAD ONE JOB: Tweeting accountant blamed for Oscar best picture blunder.

In a gaffe that stunned the Dolby Theatre crowd in Hollywood and a television audience worldwide, “[Accountant Brian] Cullinan mistakenly handed the back-up envelope for Actress in a Leading Role instead of the envelope for Best Picture” to Beatty and Dunaway, PwC said.

“Once the error occurred, protocols for correcting it were not followed through quickly enough by Mr. Cullinan or his partner.”

The Wall Street Journal and celebrity website TMZ.com reported that Cullinan had posted a backstage photo of actress Emma Stone on social network Twitter minutes before the mix-up.

The photo, from Cullinan’s Twitter account, was later deleted but was still viewable on Monday on a cached archive of the page. Cullinan could not immediately be reached for comment.

The mistake was not rectified until the “La La Land” cast and producers were on stage giving their acceptance speeches. It was left to the musical’s producer, Jordan Horowitz, to put things right.

“Guys, guys, I’m sorry. No. There’s a mistake,” Horowitz said. “‘Moonlight,’ you guys won best picture. This is not a joke.”

It took three hours for PricewaterhouseCoopers, which has been overseeing Academy Awards balloting for 83 years, initially to confirm that Beatty and Dunaway received the wrong category envelope.

PwC said it took full responsibility and apologized to the casts and crews of “La La Land” and “Moonlight.”

It’s easy enough to get distracted by Emma Stone, but that’s not what Cullinan was getting paid to do.