The War with Grandpa is a 2020 American family comedy film directed by Tim Hill, from a screenplay by Tom J. Astle and Matt Ember, based upon the novel of the same name by Robert Kimmel Smith.

Uma Thurman, Rob Riggle, Laura Marano, Cheech Marin, Jane Seymour, and Christopher Walken also star.

Ed agrees, as long as they follow the rules of engagement: they cannot damage other people's belongings and cannot tell the family about their arrangement.

Peter pulls a series of pranks, including replacing Ed's shaving cream with quick-drying foam and damaging his record player.

[5][6] The War with Grandpa was initially scheduled to be released by The Weinstein Company's Dimension Films on April 21, 2017, which was later pushed back to October 20, 2017, due to principal photography location changes.

[9] In March 2018, it was announced The Weinstein Company would no longer distribute the film,[10] and its rights were reclaimed by the producers for $2.5 million.

[11] In June 2020, 101 and Brookdale Studios acquired distribution rights to the film and set it for a September 18, 2020 release; it was later pushed back to October 9.

The website's critics consensus reads, "Fitfully funny but mostly misguided, The War with Grandpa will leave audiences with a handful of chuckles—and a lot of questions about what this talented cast was thinking.

[14] On RogerEbert.com, Christy Lemire gave the film one out of four stars, calling it "a straining comedy" featuring a "wildly overqualified" cast.

[22] Jude Dry of IndieWire gave the film a "D+" and wrote: "...the killer cast is sorely wasted on an utterly inane script about a spoiled kid who inexplicably decides he hates his very nice grandpa for moving into his room.

Based on the popular kids' book by Robert Kimmel Smith, The War with Grandpa is a sluggish hodgepodge of slapstick humor that barely holds together its illogically motivated plot.

"[23] Peter Travers, reviewing the film for ABC News, wrote: "It's an individual choice whether or not to risk bringing children to theaters to see The War with Grandpa...

"[24] In November 2020, producers Marvin and Rosa Peart announced their intentions for a sequel, titled The World War with Grandpa,[1] which was subtly foreshadowed by the final scene of the movie.