Converting xdmf file to stl format

[koroshgodarzi]

Hello,
I have a 3d mesh which I have created after warping an initial one through dolfinx, Saved it as XDMF and read it back with meshio to save it again as an stl file. But I get:
Warning: STL can only write triangle cells. No triangle cells found.
I have done the above with these lines of code:

with fe.io.XDMFFile(mesh.comm, "mesh.xdmf", "w") as xdmf:
     xdmf.write_mesh(mesh)
        
meshio_mesh = meshio.read("mesh.xdmf")
meshio.write("mesh.stl", meshio_mesh)

This is the print result of the meshio_mesh:

Number of points: 158728 Number of cells: tetra: 783179 Cell data: name_to_read

I will appreciate any help.