Known for his uncompromising and often cruel stories such as "Funny Games" and "Cache", critics were right to assume that the title of Haneke's latest film was ironic.
It stars French film royalty Isabelle Huppert and Jean-Louis Trintignant.
Several critics complained that Haneke, 75, whose last Palme d'Or was for "Amour", also starring Trintignant as a character facing the end of life, was retreading old ground.
"A curious, disconcerting and sometimes insidiously effective greatest hits tableau," was The Telegraph's Tim Robey's summary.
The Guardian's Peter Bradshaw hailed "Happy End" as "a black comedy of pure sociopathy ... as gripping as a satanically inspired soap opera, a dynasty of lost souls".
While co-star Isabelle Huppert has now made four films with Haneke, for British actor Toby Jones, it was a first.
"Before reading the script I said yes, it doesn't matter if it's one line, of course I will do anything for Michael Haneke," Jones, who plays Huppert's fiance, said.
All the actors spoke of Haneke's demanding, precise direction, not allowing them any room to diverge from his vision of the characters.