Arriving a whopping 26 years after 1997’s cult-favorite Nickelodeon comedy, “Good Burger 2” fits the streaming-era trend in which audiences seek a nostalgia bump reconnecting with old favorites, like “Coming to America” or “Hocus Pocus” — not exactly classics so much as modest pleasures from more innocent times. In this obnoxiously unfunny followup from Paramount+, stars Kel Mitchell and Kenan Thompson return as hapless fast food employees. To update the story to 2023, director Phil Traill and screenwriters Kevin Kopelow and Heath Seifert add a few new characters and a tiresome AI plot, winding up with a Thanksgiving diversion that functions just fine playing in the background as families gather for their holiday meals.

The hook here is presumably a Kenan and Kel reunion, which the movie serves up without delay: Ed (Mitchell) now owns the Good Burger restaurant, where he serves as a benevolent boss, treating his employees with empathy while never losing his enthusiasm or sense of humor. Dexter (Thompson) is an inventor trying to make ends meet. After the disastrous unveiling of his latest failed device, he’s obliged to return to his teenage job, working alongside Ed. Even by sequel logic, that setup doesn’t make a lick of sense, but at least it’s swift.

Although Mitchell and Thompson are sharing the screen in no time, the audience hardly gets a chance to appreciate their chemistry before tedious new characters are introduced and the film nosedives into a convoluted and humorless plot. A nefarious businessperson (Jillian Bell) tangentially related to a character from the first movie wants to franchise Good Burger and steal it from Ed. Aided by a shadowy lawyer (Lil Rel Howery), they manage to dupe Dexter into betraying his best friend.

That’s where AI comes in: The baddies plan to open franchises all over the world and to replace the workforce with robots that look and act like Ed. As in the first movie, our heroes join forces with the other employees to thwart the plan. Believe it or not, this simplistic plot is not the film’s problem; rather, it’s the lame jokes and repetitive dialogue that keep it from landing any laughs. The cast is essentially left stranded, mugging for the cameras as they desperately try to compensate for the undercooked script.

No one is more wasted than Thompson, who graduated from the original “Good Burger” to become a stalwart part of the “Saturday Night Live” ensemble. The sequel denies him a showcase for his obvious comedic talent. Forced into playing the straight man to Mitchell’s more flashy character, Thompson ends up explaining the wacky shenanigans happening instead of actually doing anything comedic. Almost every nonsensical line Mitchell utters is followed by a sober explanation from Thompson, suggesting the writers don’t trust the audience to get the obvious jokes. What a waste of someone who demonstrates nearly every week how uproariously funny he can be on TV.

Meanwhile, lacking anything interesting to do, Mitchell resorts to an unpleasant high-pitched voice and “aw shucks” attitude. The actor squanders the opportunity to offer something different when playing the robot version of his character, resorting to a lame fart joke and making silly expressions.

Thompson enlists a handful of his “SNL” colleagues for cameos, but the screenplay doesn’t offer them much to do. As a result, Leslie Jones, Maya Rudolph and Pete Davidson end up as wasted one-scene characters. Rather than writing something witty for them to play, the filmmakers seem to think that recognizing a famous face is funny in and of itself. A parody of the much lampooned Gal Gadot-led “Imagine” video from the early days of the pandemic offers a few more cameos, culminating with a sly punchline that might be this film’s only real chuckle.

Elsewhere, hysterics abound as Traill and editor Christian Hoffman struggle to find a hilarious take. Speeding up the actors’ delivery doesn’t work, nor do the shoddy special effects and obvious body doubles featured in some of the sequences. The screenplay amounts to a series of frustrating misunderstandings, followed by even more frustrating explanations, as the characters yell above one another to no avail. When a fast food sequel takes this long to make, it ought to come out tasting a lot better than “Good Burger 2.”

“Good Burger 2” is now streaming on Paramount+.