Python Error The _posixsubprocess module is not being used

check if you can import _posixsubprocess manually, subprocess tries to import this in it's code, if it produces an exception this warning is produced.

I had the same issue with a tool that was installed with conda. Turned out that there was kind of a conflicting version of subprocess32 that came from pip. Running this did the trick:

pip uninstall subprocess32
conda install -c conda-forge subprocess32 

unsetting PYTHONHOME has fixed this issue for me.