"Blender4.0" Blender could not convert the .blend file to FBX file

Unity Engine
,
9

Blender could not convert the .blend file to FBX file.
You need to use Blender 2.45-2.49 or 2.58 and later versions for direct Blender import to work.

In case someone runs across this in the future, after digging into the python script errors, I tracked the issue down to #130705 - Importing/exporting FBX with lights fails on Blender 4.3 - blender - Blender Projects which was caused by the removal of shadow_color attribute in Blender’s light component. I tested it locally by removing all light components from the .blend file that wasn’t being converted and it indeed started working again.

The fix for this is apart of Blender 4.3.1, which is currently the next release candidate.

For those wanting to know how I was able to dig into it since the error you see in Unity is generic, here is how I was able to find out what was really broken in the .blend file…

  1. Under the hood, Unity uses this python script to do the FBX conversion. Open it in your favorite text editor.
C:\Program Files\Unity\Hub\Editor\6000.0.29f1\Editor\Data\Tools\Unity-BlenderToFBX.py
  1. Edit the script so it outputs the python errors in a txt file. I set the path of the text file to the same directory as the .blend file that was giving me errors.
# Find the Blender output file
import sys
argv = sys.argv
outfile = ' '.join(argv[argv.index("--") + 1:])
# Change this path to wherever you want the text file to go
sys.stdout = open('C:\\Users\\Owner\\playground\\Blend-file-fbx-test\\Assets\\BlenderToFBX.log', 'w')
sys.stderr = sys.stdout

  1. Reimport the bad .blend file in your Unity project to generate the errors.

  2. Look at the text file to see what’s causing the issue with the FBX conversion. Here is how mine looked…

Starting blender to FBX conversion C:\Users\Owner\playground\Blend-file-fbx-test\Temp\FBXExport\a7ae260f7690c9442958b00fbd464e01.fbx

FBX export starting... 'C:\\Users\\Owner\\playground\\Blend-file-fbx-test\\Temp\\FBXExport\\a7ae260f7690c9442958b00fbd464e01.fbx'
Traceback (most recent call last):
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\__init__.py", line 596, in execute
    return export_fbx_bin.save(self, context, **keywords)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3650, in save
    ret = save_single(operator, context.scene, depsgraph, filepath, **kwargs_mod)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3519, in save_single
    fbx_objects_elements(root, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3301, in fbx_objects_elements
    fbx_data_light_elements(objects, lamp, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 595, in fbx_data_light_elements
    shadow_color = lamp.shadow_color
                   ^^^^^^^^^^^^^^^^^
AttributeError: 'PointLight' object has no attribute 'shadow_color'
Error: Python: Traceback (most recent call last):
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3519, in save_single
    fbx_objects_elements(root, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3301, in fbx_objects_elements
    fbx_data_light_elements(objects, lamp, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 595, in fbx_data_light_elements
    shadow_color = lamp.shadow_color
                   ^^^^^^^^^^^^^^^^^
AttributeError: 'PointLight' object has no attribute 'shadow_color'
Location: C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\modules\bpy\ops.py:109
Traceback (most recent call last):
  File "C:\Program Files\Unity\Hub\Editor\6000.0.29f1\Editor\Data\Tools\Unity-BlenderToFBX.py", line 40, in <module>
    bpy.ops.export_scene.fbx(filepath=outfile,
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\modules\bpy\ops.py", line 109, in __call__
    ret = _op_call(self.idname_py(), kw)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: Error: Python: Traceback (most recent call last):
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3519, in save_single
    fbx_objects_elements(root, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 3301, in fbx_objects_elements
    fbx_data_light_elements(objects, lamp, scene_data)
  File "C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\addons_core\io_scene_fbx\export_fbx_bin.py", line 595, in fbx_data_light_elements
    shadow_color = lamp.shadow_color
                   ^^^^^^^^^^^^^^^^^
AttributeError: 'PointLight' object has no attribute 'shadow_color'
Location: C:\Program Files\Blender Foundation\Blender 4.3\4.3\scripts\modules\bpy\ops.py:109