App crashes on iOS12 and below building with XCode13

An app which was running successfully on iOS9-15 now crashes on launch on iOS9-12 when building with XCode13.1 (on M1 Pro).

It crashes on unarchive of the main storyboard due to use of UITabBarAppearance which only exists on iOS13+ (see trace below).

I have not edited my storyboard file since this was working on iOS 9-15 with previous XCode versions and the crash occurs before any of my code runs.

In the hope it was a simulator-only issue (I have no old-iOS devices) I uploaded to the store but the app crashes on launch on real devices. https://apps.apple.com/nz/app/campermate-australia-nz/id1586561660

We could drop support for iOS9-11 but we still have plenty of iPhone 6 and 5 users (limited to iOS12).

How can I fix this?

2021-12-15 10:51:09.954515+1300 TTG_Explore_Australia[36783:2248622] *** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named UITabBarAppearance because no class named UITabBarAppearance was found; the class needs to be defined in source code or linked in from a library (ensure the class is part of the correct target)'
*** First throw call stack:
(
	0  CoreFoundation           0x0000000113cae8db __exceptionPreprocess + 331
	1  libobjc.A.dylib           0x0000000113259ac5 objc_exception_throw + 48
	2  CoreFoundation           0x0000000113cae735 +[NSException raise:format:] + 197
	3  UIFoundation            0x00000001176626c9 UINibDecoderDecodeObjectForValue + 360
	4  UIFoundation            0x0000000117662af9 UINibDecoderDecodeObjectForValue + 1432
	5  UIFoundation            0x0000000117662554 -[UINibDecoder decodeObjectForKey:] + 251
	6  UIKitCore              0x000000011ca0c827 -[UINib instantiateWithOwner:options:] + 1306
	7  UIKitCore              0x000000011cf28594 -[UIStoryboard instantiateViewControllerWithIdentifier:] + 181
	8  UIKitCore              0x000000011cd8c809 -[UIApplication _loadMainStoryboardFileNamed:bundle:] + 111
	9  UIKitCore              0x000000011cd8ccb1 -[UIApplication _loadMainInterfaceFile] + 274
	10 UIKitCore              0x000000011cd8b3e5 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1360
	11 UIKitCore              0x000000011c5cfa4e __111-[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:]_block_invoke + 904
	12 UIKitCore              0x000000011c5d8346 +[_UICanvas _enqueuePostSettingUpdateTransactionBlock:] + 153
	13 UIKitCore              0x000000011c5cf664 -[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:] + 236
	14 UIKitCore              0x000000011c5cffc0 -[__UICanvasLifecycleMonitor_Compatability activateEventsOnly:withContext:completion:] + 1091
	15 UIKitCore              0x000000011c5ce332 __82-[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:]_block_invoke + 782
	16 UIKitCore              0x000000011c5cdfe9 -[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:] + 433
	17 UIKitCore              0x000000011c5d2d2e __125-[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke + 576
	18 UIKitCore              0x000000011c5d3988 _performActionsWithDelayForTransitionContext + 100
	19 UIKitCore              0x000000011c5d2a95 -[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:] + 223
	20 UIKitCore              0x000000011c5d7a48 -[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
	21 UIKitCore              0x000000011cd89dc8 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 514
	22 UIKitCore              0x000000011c94102f -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 361
	23 FrontBoardServices         0x000000011aeb4d25 -[FBSSceneImpl _didCreateWithTransitionContext:completion:] + 448
	24 FrontBoardServices         0x000000011aebead6 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 283
	25 FrontBoardServices         0x000000011aebe300 __40-[FBSWorkspace _performDelegateCallOut:]_block_invoke + 53
	26 libdispatch.dylib          0x0000000114cc4db5 _dispatch_client_callout + 8
	27 libdispatch.dylib          0x0000000114cc82ba _dispatch_block_invoke_direct + 300
	28 FrontBoardServices         0x000000011aef00da __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
	29 FrontBoardServices         0x000000011aeefd92 -[FBSSerialQueue _performNext] + 451
	30 FrontBoardServices         0x000000011aef0327 -[FBSSerialQueue _performNextFromRunLoopSource] + 42
	31 CoreFoundation           0x0000000113c15db1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
	32 CoreFoundation           0x0000000113c15633 __CFRunLoopDoSources0 + 243
	33 CoreFoundation           0x0000000113c0fcef __CFRunLoopRun + 1231
	34 CoreFoundation           0x0000000113c0f4d2 CFRunLoopRunSpecific + 626
	35 GraphicsServices          0x00000001169e62fe GSEventRunModal + 65
	36 UIKitCore              0x000000011cd8cfc2 UIApplicationMain + 140
	37 TTG_Explore_Australia        0x0000000100e63dd8 main + 104
	38 ???                 0x0000000202b024fe 0x0 + 8635032830
	39 ???                 0x0000000000000003 0x0 + 3
)
libc++abi.dylib: terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named UITabBarAppearance because no class named UITabBarAppearance was found; the class needs to be defined in source code or linked in from a library (ensure the class is part of the correct target)'
terminating with uncaught exception of type NSException
CoreSimulator 776.4 - Device: iPhone 8 Plus (B0A6FB7E-392D-40E7-AC7C-B6AF109ABE60) - Runtime: iOS 12.4 (16G73) - DeviceType: iPhone 8 Plus

XCode had sneakily inserted these into my storyboard file without my knowledge!

<tabBarAppearance key="standardAppearance"/>

and

<navigationBarAppearance key="standardAppearance"/>

Deleting these fixed it! I set appearance for iOS13+ in my code within a version check.

thanks @brucewebster you saved my day! Same issue, the change was made about 5 months ago

App crashes on iOS12 and below building with XCode13
 
 
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