Error: CDO constructor (ThumbnailManager)

Following message appears when I open my 4.24 project in 4.25: “Error: CDO constructor (ThumbnailManager): Failed to find/Engine/EditorMeshes/EditorSkySphere”.

I removed a EditorSkySphere (in 4.25) from my World Outliner, but this message appears when open project and when I play standalone…