blender-interface-common-failures

name	blender-interface-common-failures
description	Sub-skill of blender-interface: Common Failures (+2).
version	1.1.0
category	engineering
type	reference
scripts_exempt	true

Common Failures (+2)

Common Failures

Error	Cause	Fix
AttributeError: 'NoneType' has no attribute 'select_set'	No active object after operation	Check bpy.context.selected_objects before accessing
RuntimeError: Operator bpy.ops.wm.stl_import not found	Blender version mismatch (3.x vs 4.x)	Use version-gated import (see migration table)
CUDA error: out of memory	GPU memory exhausted during Cycles render	Reduce tile size, lower samples, or use CPU fallback
Segmentation fault in headless	Missing display server	Set DISPLAY=:0 or use xvfb-run blender --background
bpy.ops.render.render(): Error, no camera	No camera in scene or not set as active	bpy.context.scene.camera = cam_object
Cannot read file: ...blend	Blend file version newer than Blender	Use matching Blender version or save backward-compatible
operator returned {'CANCELLED'}	Operation context incorrect	Ensure correct context override or use with bpy.context.temp_override()
enum "BLENDER_EEVEE_NEXT" not found	Blender 5.x reverted EEVEE enum name	Use version check: 'BLENDER_EEVEE_NEXT' if bpy.app.version[0]==4 else 'BLENDER_EEVEE'
DeprecationWarning: 'Material.use_nodes'	Blender 5.x always enables nodes	Guard with if bpy.app.version[0] < 5: mat.use_nodes = True

Diagnostic Function

def diagnose_blender_env():
    """Check Blender environment for common issues."""
    import bpy
    diag = {"version": bpy.app.version_string, "issues": [], "info": []}

    # Check version
    major = bpy.app.version[0]
    diag["info"].append(f"Blender {bpy.app.version_string}")
    if major < 3:
        diag["issues"].append("Blender < 3.0 — many operators unavailable")

    # Check GPU
    if bpy.context.preferences.addons.get('cycles'):
        prefs = bpy.context.preferences.addons['cycles'].preferences
        prefs.get_devices()
        gpu_devices = [d for d in prefs.devices if d.type != 'CPU']
        if gpu_devices:
            for d in gpu_devices:
                diag["info"].append(f"GPU: {d.name} ({d.type})")
        else:
            diag["issues"].append("No GPU detected — Cycles will use CPU only")

    # Check camera
    if not bpy.context.scene.camera:
        diag["issues"].append("No active camera — render will fail")

    # Check for orphaned data
    orphans = len([m for m in bpy.data.meshes  m.users == ])
     orphans > :
        diag[].append()

     diag

Headless Display Fix

# If Blender crashes with display errors on a headless server:
# Option 1: Use xvfb (X Virtual Frame Buffer)
xvfb-run -a blender --background --python script.py

# Option 2: Set EGL for GPU rendering without display
export DISPLAY=:0
export __EGL_VENDOR_LIBRARY_FILENAMES=/usr/share/glvnd/egl_vendor.d/10_nvidia.json
blender --background --python script.py