A subprocess called by pip (usually for building wheels) failed with an error. The root cause is often in the subprocess error message, not in pip itself.
Fixes How to fix 'pip subprocess error' in Python
# How to fix 'pip subprocess error' in Python
pip works by calling subprocesses: calling git to clone repos, running setup.py scripts, compiling C code. If any subprocess returns a non-zero exit code, pip reports a subprocess error and stops installation.
Review the error message above and identify which cause applies to your situation. Run additional diagnostics if needed.
Follow the corresponding solution from the causes section above.
Once you've addressed the root cause, try running 'pip install' again.