A year after host Neil Patrick Harris quipped that the Oscars were honoring Hollywood's "best and whitest," the Academy of Motion Picture Arts and Sciences unveiled yet another all-white slate of acting nominees Thursday, prompting a dismayed revival of the "OscarsSoWhite" hashtag.

Many also expressed regret that the highly admired N.W.A biopic "Straight Outta Compton" failed to score a best picture nod, despite being recognized in other contests. In acting categories, omissions included Idris Elba in "Beasts of No Nation" and Will Smith in "Concussion."

Those voicing disappointment included the academy's president herself, Cheryl Boone Isaacs.

"I really was disappointed," Isaacs told The Associated Press when asked about "Compton," which did receive a screenplay nomination (for, some noted on Twitter, its white screenwriters, not its black cast or director). "Fabulous movie, fabulous movie."

But Isaacs, who is black, added that the Oscar nominations are part of a much broader conversation in the entertainment industry about diversity — and that change would happen, albeit slowly.

"What is important is that this entire conversation of diversity is here and we are talking about it," Isaacs said. "And I think we will not just talk, because people will say, 'Well don't just talk, you gotta do,' (but) talking gets to the doing, and we are going to do. ... It is an industry-wide situation and we need to continue this conversation. We need to bring in new talent, to nourish the talent, to allow it to flourish and to give us all the diversity of storytelling which is what the motion picture business is all about."

There was widespread surprise that the lack of diversity persisted despite the marked backlash a year ago when — like this year — all acting nominees were white and there was only one director of color, eventual winner Alejandro Inarritu (also nominated Thursday, for "The Revenant"). The most notable omissions involved the lauded civil rights drama "Selma"; both its director, Ava DuVernay, and its star, David Oyelowo, were passed over.

"It's business as usual at the academy," said Gil Robertson, president of the African-American Film Critics Association, on Thursday. "We'll have to try again. After the whole debacle with 'Selma' and Ava DuVernay, you would have thought some lessons would have been learned. Nothing for Will Smith. Nothing for Idris Elba. Irony of ironies, the only actor who received a nomination for 'Creed' is white." (He was referring to Sylvester Stallone, who got a supporting actor nod for reprising his role as Rocky Balboa. Co-star Michael B. Jordan was not nominated, nor was director Ryan Coogler.)

Film producer and director Reginald Hudlin, who is co-producer of this year's Oscar telecast, called the situation "frustrating."

"Maybe if there's 50 great films by black filmmakers, they will get three nominations," said Hudlin, who produced "Django Unchained."

"And again, that's not putting down the movies that are nominated, they're wonderful," said Hudlin. "It's just a frustrating thing that the voting doesn't reflect what America is saying very loud and clear, what the world is saying very loud and clear."

Many tweeted their disapproval on Thursday.

"I love @TheSlyStallone," wrote indie director Joe Carnahan, "but Michael B. Jordan, Tessa Thompson & Ryan Coogler don't get noms for CREED!? Come on Academy."

"Zero nonwhite actors have been nominated for Oscars," tweeted the Tribeca Film Festival. "There's no excuse."

"Compton" did receive a screenwriting nod, and one of its writers said she sees hope for change on the diversity issue in Hollywood. "I was actually at a town hall meeting on diversity last night, and I think it's an exciting time to be having this conversation in Hollywood," said writer Andrea Berloff. "It is not being ignored, and there's a lot of us working at a more grassroots level to try to turn the tides."

Berloff added that there was a key positive note for women in the nominations list: four women nominated for their screenplays this year.

"That's a huge success," Berloff said, "and I hope we can really take the time to celebrate. It's a huge victory."