Editor hangs for several seconds when closing multiple asset editors

UE - Editor - Sep 24, 2026

CL 51680020 added an async write in SStandaloneAssetEditorToolkitHost::SaveTabLocation(). This can cause multi-threaded write conflicts on EditorPerProjectUserSettings.ini. As a result, the file mov ...

ImportMeshPaintTextureFromVertexColors only works with "Per Instance Vertex Colors"

UE - Editor - Aug 11, 2026

The "Import Vertex Colors" feature in mesh paint mode only works if the instance had vertex color overrides enabled. This is especially problematic for Nanite meshes since usually you can't add act ...

FAssetFixUpRedirectors::FixupReferencers cannot be run silently

UE - Editor - Aug 3, 2026

SFixupRedirectorsReport was added with 31698013. There is no way to prevent the UI from showing so the code cannot be used in unattended mode. ...

Color picker widget auto-closes unnecessarily

UE - Editor - Aug 3, 2026

A licensee reports that the color picket widget in Unreal Editor closes whenever a blueprint actor (map placed instance of an actor blueprint) receives a property changed event, even if the change e ...

Viewport Controller Camera Control Regressions in UE5.8

UE - Editor - Jul 16, 2026

In UE5.8 it appears some changes were made to the camera control and navigation in the editor viewports. You can no longer use controller and mouse simultaneously to control the camera. Previously ...

Resavepackages commandlet strips level package thumbnails

UE - Editor - May 12, 2026

When loading thumbnails in FLinkerLoad::SerializeThumbnails, the level asset has two thumbnails. The first one has a size of 0, which causes the loading process to abort early. Since the actual thum ...

Cook Non-Determinism in USplineComponent

UE - Editor - Feb 25, 2026

1. Non-Deterministic LastAuthority Serialization LastAuthority is assigned in USplineComponent::Serialize. Its value depends on the order in which the object and its archetype are serialized, leadi ...

Drag and drop does not work from a window created with PySide

UE - Editor - Feb 5, 2026

The cursor position is no longer updated during drag and drop, so drag-over events cannot respond correctly. Commenting out the following code in WindowsCursor.cpp works as a workaround ( the behavi ...