Hello all, We got app crashes on dataSource.apply(snapshot, animatingDifferences: false) after refactoring our tableView code to UITableViewDiffableDataSource. This doesn't happen every time. DispatchQueue.main.async { [weak self] in guard let self = self else { return } var snapshot = getCurrentSnapshot() snapshot.deleteItems([...]) snapshot.appendItems([...], toSection: section) dataSource.apply(snapshot, animatingDifferences: false) } And the controller has deallocated before it. Crash log: controller (0x110a64800): deallocated *** Assertion failure in NSInteger _UITableViewRowDataNumberOfRowsInSection(UITableViewRowData *__unsafe_unretained, NSInteger)(), UITableViewRowData.m:1761 *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Requested the number of rows for section (4) which is out of bounds.' *** First throw call stack: ( 0 CoreFoundation 0x0000000180491128 __exceptionPreprocess + 172 1 libobjc.A.dylib 0x000000018008412c objc_exception_throw + 56 2 Foundation 0x0000000180d11770 -[NSMutableDictionary(NSMutableDictionary) classForCoder] + 0 3 UIKitCore 0x0000000185538ad0 -[UITableViewRowData numberOfRowsInSection:] + 260 4 UIKitCore 0x00000001855052f0 -[UITableView _shouldDrawSeparatorAtBottomOfSectionForCellAtIndexPath:] + 152 5 UIKitCore 0x0000000185504dbc -[UITableView _updateSeparatorStateForCell:atIndexPath:] + 100 6 UIKitCore 0x0000000185504cf0 -[UITableView _updateSeparatorStateForVisibleCells] + 188 7 UIKitCore 0x00000001854f4bd0 -[UITableView _updateAnimationDidStopWithOldVisibleViews:finished:context:] + 1108 8 UIKitCore 0x00000001854f2630 __46-[UITableView _updateWithItems:updateSupport:]_block_invoke_4 + 36 9 UIKitCore 0x00000001857fcb1c __UIVIEW_IS_EXECUTING_ANIMATION_COMPLETION_BLOCK__ + 28 10 UIKitCore 0x00000001857fce24 -[UIViewAnimationBlockDelegate _sendDeferredCompletion:] + 100 11 libdispatch.dylib 0x000000010e5100f0 _dispatch_call_block_and_release + 24 12 libdispatch.dylib 0x000000010e51193c _dispatch_client_callout + 16 13 libdispatch.dylib 0x000000010e5215e4 _dispatch_main_queue_drain + 1228 14 libdispatch.dylib 0x000000010e521108 _dispatch_main_queue_callback_4CF + 40 15 CoreFoundation 0x00000001803f1a30 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12 16 CoreFoundation 0x00000001803ec148 __CFRunLoopRun + 1936 17 CoreFoundation 0x00000001803eb5a4 CFRunLoopRunSpecific + 572 18 GraphicsServices 0x000000018e9fbae4 GSEventRunModal + 160 19 UIKitCore 0x00000001852f02e4 -[UIApplication _run] + 868 20 UIKitCore 0x00000001852f3f5c UIApplicationMain + 124 21 appName 0x0000000103e8b0dc $s22appNameySpySpys4Int8VGGXEfU_ + 192 22 appName 0x0000000103e8b480 _swift_se0333_UnsafeMutablePointer_withMemoryRebound + 900 23 appName 0x0000000103e8af30 main + 1320 24 dyld 0x000000010e409544 start_sim + 20 25 ??? 0x000000010e61a0e0 0x0 + 4536246496 26 ??? 0xca54000000000000 0x0 + 14579277893705138176 ) libc++abi: terminating due to uncaught exception of type NSException