When using pip of python 3, what does "can't combine user with prefix, exec_prefix/home, or install_(plat)base" mean? And How do I fix it?

When I run the following pip command:

pip3 install -r requirements.txt --upgrade --force-reinstall --ignore-installed --target target/classes/python  

I got the following error:

Exception:  Traceback (most recent call last):    File "/usr/lib/python3/dist-packages/pip/basecommand.py", line 215, in main      status = self.run(options, args)    File "/usr/lib/python3/dist-packages/pip/commands/install.py", line 360, in run      prefix=options.prefix_path,    File "/usr/lib/python3/dist-packages/pip/req/req_set.py", line 784, in install      **kwargs    File "/usr/lib/python3/dist-packages/pip/req/req_install.py", line 851, in install      self.move_wheel_files(self.source_dir, root=root, prefix=prefix)    File "/usr/lib/python3/dist-packages/pip/req/req_install.py", line 1064, in move_wheel_files      isolated=self.isolated,    File "/usr/lib/python3/dist-packages/pip/wheel.py", line 247, in move_wheel_files      prefix=prefix,    File "/usr/lib/python3/dist-packages/pip/locations.py", line 153, in distutils_scheme      i.finalize_options()    File "/usr/lib/python3.6/distutils/command/install.py", line 274, in finalize_options      raise DistutilsOptionError("can't combine user with prefix, "  distutils.errors.DistutilsOptionError: can't combine user with prefix, exec_prefix/home, or install_(plat)base  

What does it mean?
I'm not even using any of the options among '--user', '--prefix', '--home' or '--install*', so where does the can't combine part come from?

https://stackoverflow.com/questions/65432320/when-using-pip-of-python-3-what-does-cant-combine-user-with-prefix-exec-pref December 24, 2020 at 07:49AM