I have a similar crash that I'm looking into when using the iPadAir (5th generation) (17.0.1) simulator. I am thinking it is either to do with a keyboard pop-up or my updating of @State variables that are used to refresh a view (which is in the background of a .sheet) *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Modifications to the layout engine must not be performed from a background thread after it has been accessed from the main thread.' *** First throw call stack: ( 0 CoreFoundation 0x000000018048d8a8 __exceptionPreprocess + 172 1 libobjc.A.dylib 0x000000018008409c objc_exception_throw + 56 2 CoreAutoLayout 0x00000001ca3ad284 -[NSISEngine tryToOptimizeReturningMutuallyExclusiveConstraints] + 0 3 CoreAutoLayout 0x00000001ca3ad664 -[NSISEngine withBehaviors:performModifications:] + 32 4 UIKitCore 0x00000001857bbffc -[UIView _postMovedFromSuperview:] + 448 5 UIKitCore 0x00000001857c8c10 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 2192 6 UIKitCore 0x0000000184d8e1e4 -[_UITextLayoutCanvasView textViewportLayoutController:configureRenderingSurfaceForTextLayoutFragment:] + 496 7 UIFoundation 0x0000000184674d90 __48-[NSTextViewportLayoutController layoutViewport]_block_invoke_4 + 140 8 UIFoundation 0x000000018461708c __80-[NSTextLayoutManager enumerateViewportElementsFromLocation:options:usingBlock:]_block_invoke + 36 9 UIFoundation 0x000000018461260c __83-[NSTextLayoutManager enumerateTextLayoutFragmentsFromLocation:options:usingBlock:]_block_invoke_3 + 624 10 CoreFoundation 0x00000001803f245c NSARRAY_IS_CALLING_OUT_TO_A_BLOCK + 16 11 CoreFoundation 0x00000001804d537c -[__NSSingleObjectArrayI enumerateObjectsWithOptions:usingBlock:] + 88 12 UIFoundation 0x0000000184612258 __83-[NSTextLayoutManager enumerateTextLayoutFragmentsFromLocation:options:usingBlock:]_block_invoke + 1400 13 UIFoundation 0x0000000184611bf0 -[NSTextLayoutManager enumerateTextLayoutFragmentsFromLocation:options:usingBlock:] + 952 14 UIFoundation 0x000000018461705c -[NSTextLayoutManager enumerateViewportElementsFromLocation:options:usingBlock:] + 72 15 UIFoundation 0x0000000184674840 -[NSTextViewportLayoutController layoutViewport] + 1340 16 UIKitCore 0x00000001857c2cf4 +[UIView(Animation) performWithoutAnimation:] + 68 17 UIKitCore 0x0000000184d8de54 -[_UITextLayoutCanvasView _performViewportLayout] + 112 18 UIKitCore 0x00000001857cdb1c -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1492 19 QuartzCore 0x0000000189f6fdd4 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 440 20 QuartzCore 0x0000000189f7ab30 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 124 21 QuartzCore 0x0000000189e963bc _ZN2CA7Context18commit_transactionEPNS_11TransactionEdPd + 460 22 QuartzCore 0x0000000189ec5bf0 _ZN2CA11Transaction6commitEv + 652 23 QuartzCore 0x0000000189ec6670 _ZN2CA11Transaction14release_threadEPv + 228 24 libsystem_pthread.dylib 0x0000000100dd1100 _pthread_tsd_cleanup + 616 25 libsystem_pthread.dylib 0x0000000100dd3b9c _pthread_exit + 80 26 libsystem_pthread.dylib 0x0000000100dd0dfc pthread_exit + 0 27 libsystem_pthread.dylib 0x0000000100dcf9ac _pthread_wqthread + 420 28 libsystem_pthread.dylib 0x0000000100dce6e4 start_wqthread + 8 ) libc++abi: terminating due to uncaught exception of type NSException