"Blender 5.2 removed Scene.node_tree compositor API"

A headless render using the classic transparent-film + Cycles shadow-catcher + Alpha-Over compositor recipe comes out pure white (or wrong) on Blender 5.2. No error or exception is raised — the compositor graph just never runs.

Blender 5.2 removed Scene.node_tree and CompositorNodeComposite. The compositor is now a node group on scene.compositing_node_group, and the final image comes from a NodeGroupOutput interface socket instead of a CompositorNodeComposite node.

Scripts that set up compositor nodes via the old API silently fail — the attribute access doesn't raise an error, but the graph is never built, so the render output is whatever the default produces (typically an uncomposited or blank image).

Check bpy.app.version before trusting any pre-5.2 compositor script:

if bpy.app.version >= (5, 2, 0):
    # Use scene.compositing_node_group + NodeGroupOutput
    pass
else:
    # Use scene.node_tree + CompositorNodeComposite
    pass

Alternatively, sidestep the compositor entirely with an opaque floor render recipe that needs no compositor graph at all — render fully opaque with a matched world/floor color (emissive-grey world shader at the target backdrop RGB, a large diffuse floor whose sun-lit albedo matches, the subject's own cast shadow for contact shadow). This is immune to further compositor API changes.

The Blender 5.2 compositor redesign moved the node graph from a scene-level tree to a reusable node group. Scripts must target the new API or avoid the compositor entirely. The opaque-floor approach is future-proof because it produces the correct output from the render engine alone, without post-processing.