Is a trial court's erroneous instruction adding an extra element to a plaintiff's burden of proof harmless?

As a general matter, "[w]hen the trial court erroneously adds an extra element to the plaintiffs burden of proof, it is unlikely that the error will be harmless." Sanders v. City of Newport , 657 F.3d 772, 781 (9th Cir. 2011) (internal alterations and quotation marks omitted) (quoting Clem v. Lomeli , 566 F.3d 1177, 1182 (9th Cir. 2009) ). We have therefore concluded that a district courts erroneous instruction adding an unnecessary element to a plaintiffs burden of proof is not harmless when "it is impossible to determine from the jurys verdict and evidentiary record that the jury would have reached the same result had it been properly instructed." Id. at 78283.