Steps to reproduce: Create a default document-based app for iOS using SwiftUI or UIKit with UIDocumentViewController. In the document loading method, simulate an error by throwing an exception, for example: throw CocoaError(.coderValueNotFound) Open the app on device/simulator running iOS 18 and attempt to open or create a new document. Expected behavior: An appropriate error message should be displayed to the user. Actual behavior: No error message is shown to the user The "Create Document" button becomes permanently disabled The app appears to hang or become unresponsive Environment: iOS 18, 26 beta 9 Both UIKit and SwiftUI implementations affected Has anyone encountered this issue or found a workaround? This seems like a regression in iOS 18's document handling. FB20189617, FB20189669