#Another forgettable Robert De Niro comedy

Who knew a dodgeball game between Robert De Niro, Christopher Walken, Cheech Marin, Jane Seymour and a bunch of rowdy kids could be so bland?

That’s one of many beige scenes in the new comedy “The War With Grandpa,” a film that’s both by-the-book and based on a book, in which a preteen boy gets back at his grandfather for moving into his room.

That could have been an emotionally involving tussle. At one end, you have a young man, Peter (Oakes Fegley), who is just starting to gain his independence — represented by the almighty lockable bedroom — and at the other, a man in his 70s, Ed (De Niro), whose autonomy is slipping away. Neither really has genuine freedom.

This film dips its toes into that idea, but mostly goes gung-ho for recycled old-folks jokes and tame pranks.

Peter formally declares war on Ed in the manner of our founding fathers: “When in the course of human events one person steals another person’s bedroom, there is no other choice but war,” he writes to gramps. “You have 24 hours to give me back what is mine or face the consequences.”

His punishment is a series of high jinks that “Home Alone” would balk at. Peter sends a remote-controlled toy car with a loud radio attached to wake Ed, puts a rash-causing skin irritant in his shaving cream and tries other such annoyances that aren’t funny. Director Tim Hill’s style throughout is Zen calm, and nothing is jubilant or upsetting, like an Enya song.

Naturally, in nice family movies, kids don’t stay angry at their grandparents for too long, so gradually the duo de-escalates the skirmish and begins bonding. Peter’s mom is played by Uma Thurman, but that doesn’t matter.

“The War With Grandpa” is part of a genre of films that takes legendary actors and practically sands down their edges and ensures they don’t make a strong impression (“Book Club,” “Poms”). I expect that sort of drudgery from De Niro (for every “Irishman,” he makes 10 “Dirty Grandpa”s), but it’s a shame from Walken and Marin, men so recognizable they should be on postage stamps. Here they’re shells of themselves. And Seymour, who’s gorgeous as ever, has been unrealistically cast as a supermarket clerk and the film doesn’t even make a gag out of it.

“Grandpa” is, at least, not as moronic as much of De Niro’s recent résumé. But that’s a low, low bar.