This is a regression tested in //UE4/Release-4.27 CL#18319896
Fatal error is thrown and the Editor crashes when changing details of an animation in an Animation Composite.
Expected Results:
The animation composite is saved and the changes are preserved.
Actual Results:
The editor crashes with a Fatal Error:
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff
=== Critical error: === Fatal error! Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff [Callstack] 0x00007fff7559188d UnrealEditor-DetailCustomizations.dll!UE::Core::Private::Function::TFunctionRefCaller<<lambda_f5fead091f020843888c8d8eb8388213>,TOptional<int> __cdecl(void)>::Call() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Templates\Function.h:539] [Callstack] 0x00007fff7560aac5 UnrealEditor-DetailCustomizations.dll!TBaseFunctorDelegateInstance<TOptional<int> __cdecl(void),FDefaultDelegateUserPolicy,TFunction<TOptional<int> __cdecl(void)> >::Execute() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:831] [Callstack] 0x00007fff7563685a UnrealEditor-DetailCustomizations.dll!TAttribute<TOptional<int> >::Get() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Misc\Attribute.h:236] [Callstack] 0x00007fff756725c0 UnrealEditor-DetailCustomizations.dll!SNumericEntryBox<int>::OnGetValueForSpinBox() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Input\SNumericEntryBox.h:489] [Callstack] 0x00007fff7560b701 UnrealEditor-DetailCustomizations.dll!TBaseSPMethodDelegateInstance<1,SNumericEntryBox<int> const ,1,int __cdecl(void),FDefaultDelegateUserPolicy>::Execute() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:290] [Callstack] 0x00007fff756a65e8 UnrealEditor-DetailCustomizations.dll!SSpinBox<int>::TextField_OnTextCommitted() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Input\SSpinBox.h:878] [Callstack] 0x00007fff756213f2 UnrealEditor-DetailCustomizations.dll!TBaseSPMethodDelegateInstance<0,SSpinBox<int>,1,void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:307] [Callstack] 0x00007fff91981803 UnrealEditor-Slate.dll!FSlateEditableTextLayout::HandleFocusLost() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Text\SlateEditableTextLayout.cpp:831] [Callstack] 0x00007fff91715e79 UnrealEditor-Slate.dll!FSlateApplication::SetUserFocus() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:2847] [Callstack] 0x00007fff91716700 UnrealEditor-Slate.dll!FSlateApplication::SetUserFocus() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:2701] [Callstack] 0x00007fff9170eeb0 UnrealEditor-Slate.dll!FSlateApplication::RoutePointerDownEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:4890] [Callstack] 0x00007fff916f8b10 UnrealEditor-Slate.dll!FSlateApplication::ProcessMouseButtonDownEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:4779] [Callstack] 0x00007fff916ed169 UnrealEditor-Slate.dll!FSlateApplication::OnMouseDown() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:4677] [Callstack] 0x00007ffff55fa992 UnrealEditor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2218] [Callstack] 0x00007ffff55e9247 UnrealEditor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2699] [Callstack] 0x00007ffff55fce51 UnrealEditor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:1078] [Callstack] 0x00007ffff55e49a7 UnrealEditor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:916] [Callstack] 0x00007ff80cdb5c0d USER32.dll!UnknownFunction [] [Callstack] 0x00007ff80cdb58de USER32.dll!UnknownFunction [] [Callstack] 0x00007fff4faf66f2 InkObj.dll!UnknownFunction [] [Callstack] 0x00007fffcaea1028 atlthunk.dll!UnknownFunction [] [Callstack] 0x00007ff80cdb5c0d USER32.dll!UnknownFunction [] [Callstack] 0x00007ff80cdb5602 USER32.dll!UnknownFunction [] [Callstack] 0x00007ffff55fe148 UnrealEditor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsPlatformApplicationMisc.cpp:138] [Callstack] 0x00007ff6acef7114 UnrealEditor.exe!FEngineLoop::Tick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:5139] [Callstack] 0x00007ff6acf10d9c UnrealEditor.exe!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:183] [Callstack] 0x00007ff6acf10e8a UnrealEditor.exe!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:147] [Callstack] 0x00007ff6acf13c4d UnrealEditor.exe!LaunchWindowsStartup() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:283] [Callstack] 0x00007ff6acf25564 UnrealEditor.exe!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:330] [Callstack] 0x00007ff6acf28736 UnrealEditor.exe!__scrt_common_main_seh() [d:\a01\_work\6\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288] [Callstack] 0x00007ff80d867c24 KERNEL32.DLL!UnknownFunction [] [Callstack] 0x00007ff80ed6d721 ntdll.dll!UnknownFunction []
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-156001 in the post.