What must one say to preserve an error for appellate review and does Holguin-Hernandez apply beyond sentencing reasonableness?

QUESTION PRESENTED Under this Court’s precedent and that of several circuit courts, an error of criminal law is preserved for appellate review if it was “brought to the court’s attention.” Holguin-Hernandez v. United States, 589 U.S. 169, 174 (2020). Here, counsel brought the error to the court’s attention by saying, “Your Honor, I think the government’s come pretty close to violating the plea agreement. It sure sounds like they’re advocating for those two points, and they can’t do that.” The district court responded, “Well, I asked him what he thought.” Counsel replied, “I understand, Your Honor. But if you ask him to violate the plea agreement, it doesn’t mean he doesn’t violate the plea agreement.” The Sixth Circuit panel split. The majority denied that the error of violating the plea agreement by advocating for a prohibited two-point enhancement was preserved. Therefore, it applied plain error review instead of de novo review, affirmed Mr. Kelsey’s prison sentence, and denied him his requested remedy to revoke his guilty plea and go to trial. The highly important question that affects nearly every case that arises on appellate review is: 1. What must one say to preserve an error for appellate review? A related, important question on which the Sixth Circuit split with the Tenth, Eleventh, and D.C. Circuits is: 2. Does Holguin-Hernandez apply in cases other than those involving the substantive reasonableness of a criminal sentence?