The air was still damp after thunderstorms as guests began arriving around 9 p.m. from the Lincoln Center, whether they had watched the festival’s kickoff screening of “May December,” a drama-thriller clearly inspired by the true story of Mary Kay Letourneau, a teacher who raped and later married her former sixth-grade student.

Guests followed a maze of white weatherproof tents from the restaurant to a courtyard that backs directly onto the 843-acre park. DJs oontz-oontzed from their booths. Party sponsor Campari served a menu of negronis, spritzes and Garibaldis, complete with branded “NYFF” ice cubes, and light displays bathed partygoers in the aperitif’s signature rich, flattering carmine.

Still, something felt a little off. A little melancholy. While thousands of movie and TV writers are celebrating the end of a nearly five-month work stoppage that crippled Hollywood, the industry’s actors remain on strike, prohibited from promoting their projects, and therefore conspicuously absent from the festival.

Last year, Greta Gerwig, Adam Driver, Don Cheadle, Lars Eidinger and Jodie Turner-Smith were on hand for the festival’s first day, talking up their roles in Noah Baumbach’s “White Noise.”

By contrast, the audience at the Lincoln Center on Friday applauded screenwriter Samy Burch, who was able to make her first promotional appearance for “May December” now that the writers strike has ended. And director Todd Haynes gave a speech lamenting the absence of cast members such as Natalie Portman, Charles Melton and Julianne Moore, who plays a middle-aged woman married to the man she had an illegal sexual relationship with when he was a child.

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“There are some missing people here tonight, and I confess I’m still in a bit of a state of denial, that things didn’t get resolved the way we thought they would before tonight,” Haynes said. “We miss you guys. We stand by you.”

Friday’s festivities weren’t entirely devoid of actors, who are prohibited by their union from promoting their films, but not partying in general. There’s even the chance that an A-lister could turn up later in the 17-day event — as Julia Louis-Dreyfus did at the Telluride Film Festival this month, and Adam Driver and Patrick Dempsey did in Venice.

But the strike overshadows everything, and many actors have been reluctant to attend even those events they are allowed to, concerned about the optics of solidarity.

The whole night was a strange mix of rumination and celebration.

The courtyard party was lively and shoulder-to-shoulder for hours. VIPs like the filmmaker Laura Poitras, composer Nicholas Britell and journalist Ronan Farrow feasted at ever-refilling buffet tables, and the coat checks stayed busy with late-arriving guests well past 11 o’clock, when the passed hors d’oeuvres turned from tuna tartare and croquettes to dainty slices of cheesecake and pineapple cake.

“You feel a real lack, without the actors,” said Christine Vachon, the producer of “May December.” “I think it’s really hard, for example, on somebody like Charles Melton — who is a true discovery in ‘May December’ — that he can’t be here celebrating his film.”

One of the few actors in attendance — Jeremy O. Harris, who attended as a guest and is not promoting any projects at the New York Film Festival — looked for a silver lining in the lack of celebrities as he passed the time at the fourth major film festival since the actors strike began.

“It feels more European,” Harris said, “in the sense that there’s more of a focus on the film.”