Unable to read 3D mesh when running script in parallel

mesh
2

I cannot reproduce your error with:

docker run -ti -v $(pwd):/fenics/shared -w /fenics/shared --rm --shm-size=512m dolfinx/dolfinx:stable

and

from mpi4py import MPI
from dolfinx.io.gmshio import read_from_msh

mesh, ct, ft = read_from_msh("mesh2.msh", MPI.COMM_WORLD, 0)

mpirun -n 16 python3 mwe123.py 
Info    : Reading 'mesh2.msh'...
Info    : 422 entities
Info    : 174656 nodes
Info    : 169404 elements                                               
Info    : Done reading 'mesh2.msh'

Also, your script did not show how you converted the msh file to xdmf.