blender-errors-data

Quick Reference

Critical Rules

NEVER store direct bpy.data references (objects, meshes, materials) across undo/redo, file load, or file revert operations — ALL Python pointers to Blender data are invalidated.

NEVER access a data block after calling bpy.data.<collection>.remove() on it — the StructRNA is freed and access raises ReferenceError.

NEVER assume bpy.data.<collection>.new(name) returns the exact name you passed — Blender appends .001, .002, etc. when a name already exists.

NEVER keep references to CollectionProperty items across .add() or .remove() calls — the underlying C array is re-allocated, invalidating all prior element pointers.

NEVER use del obj["prop"] to reset RNA-defined properties in Blender 5.0+ — use obj.property_unset("prop") instead.

NEVER use obj["cycles"] dict-like access for system properties in Blender 5.0+ — system properties are separated from custom properties.

ALWAYS store object/data block names (strings) or stable identifiers instead of direct bpy references when the reference must survive across operator execution, undo, or file operations.