An access violation occurs in FNiagaraSkeletalMeshRegionBoneFilterDetails::HandleBoneNameComboBoxSelectionChanged() due to StringItem is nullptr.
SkeletalMeshRegionCustomization.cpp void FNiagaraSkeletalMeshRegionBoneFilterDetails::HandleBoneNameComboBoxSelectionChanged(TSharedPtr<FName> StringItem, ESelectInfo::Type SelectInfo) { BoneNameHandle->SetValue(*StringItem); }
The workaround is to close and reopen the Skeletal Mesh Editor.
Assertion failed: IsValid() [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Templates\SharedPointer.h] [Line: 1102] UnrealEditor_Persona!FNiagaraSkeletalMeshRegionBoneFilterDetails::HandleBoneNameComboBoxSelectionChanged() [D:\build\++UE5\Sync\Engine\Source\Editor\Persona\Private\Customization\SkeletalMeshRegionCustomization.cpp:104] UnrealEditor_Persona!V::TBaseSPMethodDelegateInstance::ExecuteIfSafe() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:298] UnrealEditor_Persona!TDelegate<void __cdecl(TSharedPtr<FName,1>,ESelectInfo::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateSignatureImpl.inl:570] UnrealEditor_Persona!SComboBox<TSharedPtr<FName,1> >::OnSelectionChanged_Internal() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Input\SComboBox.h:617] UnrealEditor_Persona!V::TBaseSPMethodDelegateInstance::ExecuteIfSafe() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:298] UnrealEditor_Persona!TDelegate<void __cdecl(TSharedPtr<FName,1>,ESelectInfo::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateSignatureImpl.inl:570] UnrealEditor_Persona!SListView<TSharedPtr<FName,1> >::Private_SignalSelectionChanged() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views\SListView.h:997] UnrealEditor_Persona!SListView<TSharedPtr<FName,1> >::UpdateSelectionSet() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views\SListView.h:1343] UnrealEditor_Slate!STableViewBase::Tick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Views\STableViewBase.cpp:337] UnrealEditor_SlateCore!SWidget::Paint() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Widgets\SWidget.cpp:1483] UnrealEditor_Slate!SBox::OnPaint() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Layout\SBox.cpp:305] UnrealEditor_SlateCore!SWidget::Paint() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Widgets\SWidget.cpp:1622] UnrealEditor_SlateCore!SCompoundWidget::OnPaint() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Widgets\SCompoundWidget.cpp:46] UnrealEditor_Slate!SBorder::OnPaint() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Widgets\Layout\SBorder.cpp:129] UnrealEditor_SlateCore!SWidget::Paint() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Widgets\SWidget.cpp:1622] UnrealEditor_SlateCore!FSlateWindowElementList::FDeferredPaint::ExecutePaint() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Rendering\DrawElements.cpp:122] UnrealEditor_SlateCore!FSlateWindowElementList::PaintDeferred() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Rendering\DrawElements.cpp:147] UnrealEditor_SlateCore!SWindow::PaintWindow() [D:\build\++UE5\Sync\Engine\Source\Runtime\SlateCore\Private\Widgets\SWindow.cpp:2126] UnrealEditor_Slate!FSlateApplication::DrawWindowAndChildren() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1159] UnrealEditor_Slate!FSlateApplication::DrawWindowAndChildren() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1211] UnrealEditor_Slate!FSlateApplication::DrawWindowAndChildren() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1211] UnrealEditor_Slate!FSlateApplication::PrivateDrawWindows() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1394] UnrealEditor_Slate!FSlateApplication::DrawWindows() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1103] UnrealEditor_Slate!FSlateApplication::TickAndDrawWidgets() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1698] UnrealEditor_Slate!FSlateApplication::Tick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:1549] UnrealEditor!FEngineLoop::Tick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:6047] UnrealEditor!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:180] UnrealEditor!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:118] UnrealEditor!LaunchWindowsStartup() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:258] UnrealEditor!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:298] UnrealEditor!__scrt_common_main_seh() [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288] kernel32 ntdll
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-217994 in the post.