Whether the Eighth Circuit erred in ruling that the defendant waived his jurisdictional challenge by pleading guilty, despite the well-settled principle that subject-matter jurisdiction cannot be waived

QUESTIONS PRESENTED It is well settled that subject-matter jurisdictional challenges cannot be waived. The Eighth Circuit ruled that Reed's jurisdictional challenge(s) were “foreclosed by his guilty plea." Did the Eighth Circuit err in it's Penson review, when it ruled --without merits briefing-that Reed waived 'the very power of the' District Court to hear his case? Class V. United States, 138 S. Ct. 798, 800 (2017) ; , United States V. Cotton, 535 U.S. 625, 630 (2002) Blackledge V. Perry, 417 Us. 21, 30 (1974)