Bug#1145118: adios4dolfinx: FTBFS: E ValueError: [Sat Aug 22 10:11:38 2026] [ADIOS2 EXCEPTION] <Core> <IOHDF5> <MakeEngineHDF5> : A serial HDF5 engine cannot be used with a communicator that is MPI-based.

[Francesco Ballarin]

Source: adios4dolfinx
Followup-For: Bug #1145118
Control: tags -1 ftbfs

Hi,
I believe that the issue is somewhere in adios2 and/or hdf5, not here.



In a clean container with only
# apt install openmpi-bin python3-adios2-mpi python3-mpi4py



use the following test

$ cat test.py
from mpi4py import MPI
import adios2.bindings as adios2

comm = MPI.COMM_WORLD

adios = adios2.ADIOS(comm)
io = adios.DeclareIO("TestIO")
io.SetEngine("HDF5")

engine = io.Open("test.h5", adios2.Mode.Write)
engine.Close()




$ mpirun -n 2 python3 test.py
Traceback (most recent call last):
Traceback (most recent call last):
  File "/home/test.py", line 10, in <module>
    engine = io.Open("test.h5", adios2.Mode.Write)
ValueError: [Thu Sep 03 17:01:51 2026] [ADIOS2 EXCEPTION] <Core> <IOHDF5> <MakeEngineHDF5> : A serial HDF5 engine cannot be used with a communicator that is MPI-based.

  File "/home/test.py", line 10, in <module>
    engine = io.Open("test.h5", adios2.Mode.Write)
ValueError: [Thu Sep 03 17:01:51 2026] [ADIOS2 EXCEPTION] <Core> <IOHDF5> <MakeEngineHDF5> : A serial HDF5 engine cannot be used with a communicator that is MPI-based.





Cheers,
Francesco