Hi everyone, sorry for the monologue but I found a ‘partial’ solution to my problem so I figured it might be useful to other people. I also think this is a bug report, but I might be wrong.
Since the beginning of 2024, the default version of the hdf5 package on conda-forge is 1.14.3. After comparing the packages with an older installation I had of an older version of dolfinx that was running complex eigensolvers fine, I tried to install dolfinx in a conda env as follows :
conda install -c conda-forge python=3.10 mpich fenics-dolfinx hdf5=1.14.2 petsc=*=complex* slepc=*=complex*
to downgrade the hdf5 package. This solved my problem : I can now run the demo with a complex build in parallel with MUMPS.
This command does not install the latest stable release 0.7.3 of dolfinx, but the 0.7.1. It also does not install the latest releases of petsc, slepc and mumps. I haven’t looked too much for a way to have both the latest version of dolfinx and hdf5 1.14.2 as this is enough for me for now.