Following MWE missed a mesh vertex in the definition of x. Crashes with a hard to debug error of
MPI_ERR_RANK: invalid rank
from mpi4py import MPI
import numpy as np
import ufl
import basix
import dolfinx
import basix.ufl
x = np.array([[1, 0], [2, 0]], dtype=np.float64) # missed [3, 0]
cells = np.array([[0, 1], [1, 2]], dtype=np.int64)
element = ufl.Mesh(basix.ufl.element("Lagrange", "interval", 1, shape=(2,)))
mesh = dolfinx.mesh.create_mesh(MPI.COMM_WORLD, cells, element, x) # <- crashes here
In a Debug build this hits the assertion in MPI.h::index_owner. A similar output should be available in Release - but not raised from index_owner due to performance impact - rather as an input argument check.