In Unreal Engine version 5.5.4, the Editor crashes when performing Undo after deleting a Material Layer of a Material Instance
Repro steps:
1. Create a new material
Right-click in the Content Browser, click "Material" and create a new material.
Set it to any material name (e.g. M_Test).
2. Add a material layer
Double-click the material you created to open the Material Editor.
Right-click in the Node Graph and add a "Material Attribute Layers" node.
Click "Apply" in the upper left of the editor to compile, then press Ctrl + S to save the changes to the asset.
3. Create a Material Instance
Right-click on the material “M_Test” created in the previous step and create a material instance from “Create Material Instance”.
Set it to any material name (e.g. MI_Test).
4. Adding and deleting material layers
Double-click the Material Instance to open the Material Instance Editor.
Click “Window” from the menu at the top of the editor, then click “Layer Parameters” to display the tab for editing material layers.
Click the “+” button in Material Layers and create a new layer called “Layer 1”.
Click the “X” button to the right of the created material layer “Layer 1” to delete the layer.
5. Undo the operation that caused the crash
Use the keyboard shortcut Ctrl+Z to Undo.
6. Check for crashes
The editor freezes and then crashes after a few seconds.
Expected Behavior
Undo (Ctrl+Z) no longer crashes the editor and restores deleted layers.
UnrealEditor_Core!FDebug::CheckVerifyFailedImpl2() [AssertionMacros.cpp:726]
UnrealEditor_Engine!FMaterialLayersFunctions::Validate() [MaterialExpressions.cpp:16926]
UnrealEditor_Engine!UMaterialInstance::GetMaterialLayers() [MaterialInstance.cpp:2850]
UnrealEditor_Engine!UMaterialInstanceConstant::UpdateCachedData() [MaterialInstanceConstant.cpp:195]
UnrealEditor_Engine!UMaterialInstance::PostEditChangeProperty() [MaterialInstance.cpp:4545]
UnrealEditor_Engine!UMaterialInstanceConstant::PostEditChangeProperty() [MaterialInstanceConstant.cpp:73]
UnrealEditor_CoreUObject!UObject::PostEditChange() [Obj.cpp:477]
UnrealEditor_UnrealEd!FTransaction::Apply() [EditorTransaction.cpp:960]
UnrealEditor_UnrealEd!UTransBuffer::Undo() [EditorTransaction.cpp:1640]
UnrealEditor_UnrealEd!UEditorEngine::UndoTransaction() [EditorServer.cpp:1303]
UnrealEditor_UnrealEd!UEditorEngine::Exec_Transaction() [EditorServer.cpp:5328]
UnrealEditor_UnrealEd!UEditorEngine::Exec_Editor() [EditorServer.cpp:5728]
UnrealEditor_Core!FExec::Exec() [Exec.cpp:18]
UnrealEditor_Engine!UEngine::Exec() [UnrealEngine.cpp:5133]
UnrealEditor_UnrealEd!UUnrealEdEngine::Exec() [UnrealEdSrv.cpp:662]
UnrealEditor_MainFrame!FMainFrameActionCallbacks::ExecuteExecCommand() [MainFrameActions.cpp:634]
UnrealEditor_MainFrame!TBaseStaticDelegateInstance<void __cdecl(void) [DelegateInstancesImpl.h:801]
UnrealEditor_Slate!FUIAction::Execute() [UIAction.h:139]
UnrealEditor_Slate!FUICommandList::ConditionalProcessCommandBindings() [UICommandList.cpp:235]
UnrealEditor_Slate!FUICommandList::ProcessCommandBindings() [UICommandList.cpp:179]
UnrealEditor_MainFrame!FMainFrameActionCallbacks::OnUnhandledKeyDownEvent() [MainFrameActions.cpp:269]
UnrealEditor_MainFrame!TBaseStaticDelegateInstance<FReply __cdecl(FKeyEvent const &) [DelegateInstancesImpl.h:791]
UnrealEditor_Slate!FSlateApplication::ProcessKeyDownEvent() [SlateApplication.cpp:4869]
UnrealEditor_Slate!FSlateApplication::OnKeyDown() [SlateApplication.cpp:4756]
UnrealEditor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [WindowsApplication.cpp:2884]
UnrealEditor_ApplicationCore!FWindowsApplication::DeferMessage() [WindowsApplication.cpp:3568]
UnrealEditor_ApplicationCore!FWindowsApplication::ProcessMessage() [WindowsApplication.cpp:2723]
UnrealEditor_ApplicationCore!FWindowsApplication::AppWndProc() [WindowsApplication.cpp:1720]
UnrealEditor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [WindowsPlatformApplicationMisc.cpp:145]
UnrealEditor!FEngineLoop::Tick() [LaunchEngineLoop.cpp:5531]
UnrealEditor!GuardedMain() [Launch.cpp:187]
UnrealEditor!GuardedMainWrapper() [LaunchWindows.cpp:124]
UnrealEditor!LaunchWindowsStartup() [LaunchWindows.cpp:278]
UnrealEditor!WinMain() [LaunchWindows.cpp:335]
UnrealEditor!__scrt_common_main_seh() [exe_common.inl:288]
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-264894 in the post.
| 0 |
| Component | UE - Rendering Architecture - Materials |
|---|---|
| Affects Versions | 5.4.4 |
| Target Fix | 5.7 |
| Created | Apr 2, 2025 |
|---|---|
| Resolved | Apr 14, 2025 |
| Updated | Apr 14, 2025 |