Fatal Python error: Py_Initialize: Unable to get the locale encoding error when Python called from Abaqus subroutine

Question

I'm attempting to use Python in concert with user subroutines to change material properties of a model between analysis steps. The update script Update_Properties.py uses mpi4py and is called from the UEXTERNALDB subroutine like so:

STAT=SYSTEM("mpiexec -n 4 python /scratch/Update_Properties.py")

However, I keep getting this error:

Fatal Python error: Py_Initialize: Unable to get the locale encoding
  File "/gpfs/gpfs1/apps2/abaqus/2019/SimulationServices/V6R2019x/linux_a64/tools/SMApy/python2.7/lib/python2.7/encodings/__init__.py", line 123
    raise CodecRegistryError,\
                            ^
SyntaxError: invalid syntax

This is on a RHEL HPC, using Python 3.6.1 and Abaqus 2019. The job is submitted via SLURM. Python 3.6.1 is used in instead of Abaqus Python because the latter lacks mpi4py

I've checked to ensure Python 3.6.1 is on the PATH, and is the first Python present. I've also checked the PYTHONPATH and PYTHONHOME, both of which are not set on the system. I've noticed that when Abaqus runs, it adds a bunch of temporary entries to PYTHONPATH though.

If Update_Properties.py is directly submitted as a job, the script works just fine.

So far I have tried:

1. Specifying the full path to Python 3.6.1 in the SYSTEM() call
2. unset PYTHONPATH immediately before the call to Update_Properties.py
3. unset PYTHONHOME immediately before the call to Update_Properties.py
4. Setting PYTHONPATH to the directories containing the Python 3.6.1 install immediately before the call to Update_Properties.py
5. Calling Update_Properties.py using a bash script rather than directly

However, every time I get the aforementioned error.

I've looked at other question both on Stack Exchange and elsewhere, in particular:

External call to Python3.5 doesnot work from within Abaqus python

https://askubuntu.com/questions/640010/fatal-python-error-py-initialize-unable-to-get-the-locale-encoding-syntaxe

The answers given for these types of problems typically revolve around clearing or editing PYTHONPATH and/or PYTHONHOME which I've tried to no avail.

Answer 1

Ultimately, I bypassed this issue by using pyinstaller to turn the Update_Properties.py script into a stand-alone executable, and calling that instead.