Moonlight has won the best picture Oscar in a chaotic awards ceremony climax which mistakenly awarded the top honour to La La Land, a fiasco which stunned Hollywood and viewers around the world.
Emma Stone won best actress for La La Land.
It appeared Dunaway and Warren Beatty had an envelope containing a card naming a previous award won by La La Land, prompting visible hesitation between the two veteran actors before Dunaway went ahead and named La La Land.
Arrival, Moonlight, Fences and Hacksaw Ridge scooped acting and technical awards, denying La La Land, which had 14 nominations, a record-setting haul.