[BUG] Unable to read the. vol file of Netgen.

[LXHCSMX]

I got an error when running the following code:

from netgen.meshing import *
from netgen.csg import *
from netgen.occ import OCCGeometry
import meshio
import exportNeutral

geo = OCCGeometry("frame.step")
param = MeshingParameters(maxh = 5)
m1 = geo.GenerateMesh(param)
m1.SecondOrder()
m1.Save("frame.vol")

mesh = meshio.read("frame.vol")
mesh.write("frame.inp")

error:
raise RuntimeError(f"Unknown Netgen mesh token: {line}")

RuntimeError: Unknown Netgen mesh token: facedescriptors
frame.zip