Sample Project In iPadOS 26 beta4, when a UISplitViewController transitions to compact layout and proposes the secondary view controller, a crash occurs: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Layout requested for visible navigation bar, <UINavigationBar: 0x1018205b0; frame = (0 0; 320 54); opaque = NO; autoresize = W; gestureRecognizers = <NSArray: 0x600000d37cc0>; layer = <CALayer: 0x600000d13390>> delegate=0x102826600, when the top item belongs to a different navigation bar. topItem = <UINavigationItem: 0x101af3b20> title='Detail' style=navigator rightBarButtonItems=0x600000011e10, navigation bar = <UINavigationBar: 0x101817680; frame = (0 0; 320 54); opaque = NO; autoresize = W; gestureRecognizers = <NSArray: 0x600000d12310>; layer = <CALayer: 0x600000d116b0>> delegate=0x102826000, possibly from a client attempt to nest wrapped navigation controllers.' When we show the primary view, there is no crash. Similarly, there is no crash on beta-3. To reproduce the crash in the demo project: Launch the project on an iPad. "Try the Demo" Tap "List-Detail Pattern" To trigger the crash, select any of the list items and switch the app to a compact layout. The crash occurs because the app will attempt to propose the secondary view controller. To avoid the crasah, refrain from selecting an item in the list and switch to the compact layout. The app will not crash because it will attempt to propose the primary view controller.

In the Console, when presenting my view in a horizontally compact environment, I see: UINavigationController for collapsing UISplitViewController about to push view controller <UINavigationController: 0x107933c00> This message repeats infinitely, until the Xcode debugger eventually says: QUARANTINED DUE TO HIGH LOGGING VOLUME Of note is that this only occurs in the beta, does not occur when using the iOS 18.x SDK, and only occurs in a compact environment. EDIT: This occurs only when setting the secondary column of a doubleColumn UISplitViewController: splitVC.setViewController(secondary, for: .secondary) EDIT 2 and WORKAROUND: If this action is deferred until after viewDidAppear, it self-resolves: public override func viewDidAppear(_ animated: Bool) { super.viewDidAppear(animated) if let deferredSecondaryViewController { splitVC.showDetailViewController(deferredSecondaryViewController, sender: nil) } }