UE4.26 export to FBX with Morphs->To Blender==Python Error and No blend shapes in blender

Hello,
I’m using UE4.26 source build

  1. Export a skeletal mesh from UE4 that has morph targets/blend shapes, to FBX (I’ve tried FBX v2013 and up)

  2. Import to Blender either normally, or using the UE4 pipeline in blender

  3. The following error is given, and no blendshapes appear in blender for the imported mesh.

    Python: Traceback (most recent call last):
    File “C:\Program Files\Blender Foundation\Blender 2.91\2.91\scripts\addons\io_scene_fbx_init_.py”, line 216, in execute
    if import_fbx.load(self, context, filepath=path, **keywords) == {‘FINISHED’}:
    File “C:\Program Files\Blender Foundation\Blender 2.91\2.91\scripts\addons\io_scene_fbx\import_fbx.py”, line 2901, in load
    _(); del _
    File “C:\Program Files\Blender Foundation\Blender 2.91\2.91\scripts\addons\io_scene_fbx\import_fbx.py”, line 2899, in _
    keyblocks = blen_read_shape(fbx_tmpl, fbx_sdata, fbx_bcdata, meshes, scene)
    File “C:\Program Files\Blender Foundation\Blender 2.91\2.91\scripts\addons\io_scene_fbx\import_fbx.py”, line 1388, in blen_read_shape
    assert(len(vgweights) == nbr_indices == len(dvcos))
    AssertionError

    location: :-1

Try the same import, using an FBX file that was not exported from UE4, and it works as expected.

I’ve tried this with my own assets, I’ve even tried to export characters that I’ve gotten from the marketplace,
with the same result… Can’t import UE4 exported mesh/FBX to blender, with morph targets/blend shapes.

I DID ensure that Export Morph Targets is ticked when exporting from UE4.
Is there any known reason why this can happen?
I know it worked fine in 4.23, but I had not attemtped it since moving to 4.26.
All of my meshes/models/characters are newly imported so its not the issue about models that were imported prior to 4.25.

1 Like

I think I found the solution, you have to fix the FBX using this autodesk tool: Fbx Converter Archives

The tool is called “FBX Converter”. In the tool, you add your FBX, keep everything default, then click on “Convert” in the bottom right.

It worked with me.

2 Likes

@tofuscrambled
Absolutely, I have the converter but it never even occurred to me to try that…
Thanks!

Thank you for this! Worked for me as well