Warning: Can't cut instance(s) of <element> out of wall.
Issue: Revit cannot regenerate the geometry to display the moved model component.
If you move a door or a window (or other wall-hosted components) in such a way that Revit cannot regenerate the geometry properly, this message displays. This might happen if you move a window onto a door in a plan view. Revit cannot cut both a door instance and a window instance simultaneously. Also, the error might occur if you move a component outside a wall, by either dragging the component, or shortening the wall, such that it cannot host the component.
Solution: You can either cancel the move or delete the particular instance.