Maybe Mandatory, But Definitely Not Jurisdictional.

Kabran v. Sharp Memorial Hospital, No. S227393 (Cal Jan. 19, 2017)

The issue is whether Plaintiff’s late filing of declarations in support of a motion for new trial—to which Defendant didn’t object in the trial court—is a jurisdictional defect that can be raised as a matter of right for the first time on appeal. The Supreme Court affirms the court of Appeal in 2015’s Kabran decision and says no, for largely the same reasons.