Caused by the Cycles-X merge. The old style of tile rendering was removed, leaving the script to error out trying to set the tile size. Tile rendering came back in a new form (but only really relevant for large resolution rendering), so now leave setting auto_tile & tile_size alone (since previews are rendered at PREVIEW_RENDER_DEFAULT_HEIGHT 128 -- which should never make a difference here). Maniphest Tasks: T91808 Differential Revision: https://developer.blender.org/D12937