The app which is archived by XCode 12.5 and running on iOS 15 when I convert HTML to NSAttributedString. (iOS 14 is fine). Here is the crash report. Thread 0 name: Thread 0 Crashed: 0 libsystem_platform.dylib 0x00000001f2e5e0c0 _os_unfair_lock_recursive_abort + 36 (lock.c:508) 1 libsystem_platform.dylib 0x00000001f2e58a10 _os_unfair_lock_lock_slow + 304 (lock.c:567) 2 Foundation 0x00000001841e6730 -[NSProcessInfo(NSProcessInfoHardwareState) isLowPowerModeEnabled] + 68 (NSProcessInfo.m:708) 3 WebCore 0x0000000192499004 -[WebLowPowerModeObserver _didReceiveLowPowerModeChange] + 56 (LowPowerModeNotifier.mm:63) 4 CoreFoundation 0x00000001829bdee8 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 28 (CFNotificationCenter.c:652) 5 CoreFoundation 0x0000000182a59b9c ___CFXRegistrationPost_block_invoke + 52 (CFNotificationCenter.c:173) 6 CoreFoundation 0x0000000182a2cf54 _CFXRegistrationPost + 456 (CFNotificationCenter.c:199) 7 CoreFoundation 0x00000001829d3d54 _CFXNotificationPost + 716 (CFNotificationCenter.c:1147) 8 Foundation 0x00000001841d8028 -[NSNotificationCenter postNotificationName:object:userInfo:] + 96 (NSNotification.m:560) 9 Foundation 0x00000001842509d4 NSProcessInfoNotifyPowerState + 188 (NSProcessInfo.m:693) 10 Foundation 0x00000001841e6768 -[NSProcessInfo(NSProcessInfoHardwareState) isLowPowerModeEnabled] + 124 (NSProcessInfo.m:714) 11 WebCore 0x0000000191a1d118 -[WebLowPowerModeObserver initWithNotifier:] + 96 (LowPowerModeNotifier.mm:50) 12 WebCore 0x000000019249916c WebCore::LowPowerModeNotifier::LowPowerModeNotifier(***::Function<void (bool)>&&) + 52 (LowPowerModeNotifier.mm:76) 13 WebCore 0x00000001933bec4c WebCore::Page::Page(WebCore::PageConfiguration&&) + 1848 (memory:2099) 14 WebKitLegacy 0x00000001a64e2e34 -[WebView(WebPrivate) _commonInitializationWithFrameName:groupName:] + 3060 (WebView.mm:1568) 15 WebKitLegacy 0x00000001a64e2214 -[WebView(WebPrivate) _initWithFrame:frameName:groupName:] + 116 (WebView.mm:1715) 16 UIFoundation 0x000000018d78e028 -[NSHTMLReader _loadUsingWebKit] + 832 (NSHTMLReader.m:2570) 17 UIFoundation 0x000000018d78f15c -[NSHTMLReader attributedString] + 32 (NSHTMLReader.m:3212) 18 UIFoundation 0x000000018d7484e8 _NSReadAttributedStringFromURLOrData + 8420 (NSAttributedStringAdditions.m:2651) 19 UIFoundation 0x000000018d746378 -[NSAttributedString(NSAttributedStringUIFoundationAdditions) initWithData:options:documentAttributes:error:] + 156 (NSAttributedStringAdditions.m:1462) 20 MyAppExtensions 0x108aa0894 NSAttributedString.init(htmlString:font:useDocumentFontSize:) + 36 (__hidden#925_:36) 21 MyAppName 0x1045eca18 {foo_class}.convertHTML(_:) + 670 (xxxx.swift:670) 22 MyAppName 0x1045e5c58 {foo_class}.some_function_3 + 620 (xxxx.swift:620) 23 MyAppName 0x1045e4760 {foo_class}.some_function_2 + 212 (xxxx.swift:212) 24 MyAppName 0x1045e4200 {foo_class}.some_function_1 + 138 (xxxx.swift:138) . (some other functions related to my business logic) . . . 37 CoreFoundation 0x00000001829b5304 __invoking___ + 148 38 CoreFoundation 0x00000001829d2ad4 -[NSInvocation invoke] + 468 (NSForwarding.m:3378) 39 CoreFoundation 0x0000000182a09934 -[NSInvocation invokeWithTarget:] + 80 (NSForwarding.m:3475) 40 Lime 0x00000001037fba58 0x102838000 + 16530008 41 CoreFoundation 0x00000001829c118c ___forwarding___ + 968 (NSForwarding.m:3626) 42 CoreFoundation 0x00000001829c05c0 _CF_forwarding_prep_0 + 96 43 MyAppName 0x0000000103807558 0x102838000 + 16577880 44 MyAppName 0x000000010382084c 0x102838000 + 16681036 45 UIKitCore 0x000000018501d584 -[UIGestureRecognizerTarget _sendActionWithGestureRecognizer:] + 56 (UIGestureRecognizer.m:136) 46 UIKitCore 0x0000000184fe61d0 _UIGestureRecognizerSendTargetActions + 116 (UIGestureRecognizer.m:1481) 47 UIKitCore 0x0000000184faf05c _UIGestureRecognizerSendActions + 284 (UIGestureRecognizer.m:1520) 48 UIKitCore 0x0000000184fe8580 -[UIGestureRecognizer _updateGestureForActiveEvents] + 636 (UIGestureRecognizer.m:0) 49 UIKitCore 0x0000000184fa06fc _UIGestureEnvironmentUpdate + 1988 (UIGestureEnvironment.m:206) 50 CoreFoundation 0x00000001829d4570 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 36 (CFRunLoop.c:1804) 51 CoreFoundation 0x00000001829a3854 __CFRunLoopDoObservers + 572 (CFRunLoop.c:1917) 52 CoreFoundation 0x000000018299e8ec __CFRunLoopRun + 1052 (CFRunLoop.c:2979) 53 CoreFoundation 0x00000001829b23c8 CFRunLoopRunSpecific + 600 (CFRunLoop.c:3268) 54 GraphicsServices 0x000000019e1c338c GSEventRunModal + 164 (GSEvent.c:2200) 55 UIKitCore 0x00000001853580bc -[UIApplication _run] + 1100 (UIApplication.m:3457) 56 UIKitCore 0x00000001850d5be8 UIApplicationMain + 2124 (UIApplication.m:5013) 57 libswiftUIKit.dylib 0x0000000199f86184 UIApplicationMain(_:_:_:_:) + 104 (UIKit.swift:530) 58 Lime 0x000000010284d894 main + 180 (main.swift:7) 59 dyld 0x0000000104e59a24 start + 520 (dyldMain.cpp:876) Any thoughts? Thanks