Pip 缺少模块无法安装的问题

No module named ‘pip._internal.utils.inject_securetransport’

在使用conda的python创建新环境后，使用pip安装内容【python3.8.20】的时候，我出现过以下问题：

(vqvae) D:\1_thu_homework\airobot-lab\vqvae>pip install -r requirements.txt
Traceback (most recent call last):
  File "C:\Users\ASUS\.conda\envs\vqvae\Scripts\pip-script.py", line 6, in <module>
    from pip._internal.cli.main import main
  File "C:\Users\ASUS\.conda\envs\vqvae\lib\site-packages\pip\_internal\__init__.py", line 3, in <module>
    import pip._internal.utils.inject_securetransport  # noqa
ModuleNotFoundError: No module named 'pip._internal.utils.inject_securetransport'

(vqvae) D:\1_thu_homework\airobot-lab\vqvae>python -m pip install --upgrade pip
Traceback (most recent call last):
  File "C:\Users\ASUS\.conda\envs\vqvae\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\ASUS\.conda\envs\vqvae\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\ASUS\.conda\envs\vqvae\lib\site-packages\pip\__main__.py", line 29, in <module>
    from pip._internal.cli.main import main as _main
  File "C:\Users\ASUS\.conda\envs\vqvae\lib\site-packages\pip\_internal\__init__.py", line 3, in <module>
    import pip._internal.utils.inject_securetransport  # noqa
ModuleNotFoundError: No module named 'pip._internal.utils.inject_securetransport'

核心的问题就是pip的模块不见了，所以需要重新安装pip。

网上找到了靠谱的解决方法：

输入下列指令：

python -m ensurepip

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

python get-pip.py --force-reinstall

一般在此刻就可以解决问题了，如果你出现了类似下列问题：

(vqvae) D:\1_thu_homework\airobot-lab\vqvae>pip install -r requirements.txt
Looking in indexes: https://pypi.org/simple, https://pypi.ngc.nvidia.com
Collecting certifi==2019.3.9 (from -r requirements.txt (line 1))
  Downloading certifi-2019.3.9-py2.py3-none-any.whl.metadata (2.5 kB)
Collecting cffi==1.12.3 (from -r requirements.txt (line 2))
  Downloading cffi-1.12.3.tar.gz (456 kB)
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error

  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [1 lines of output]
      ERROR: Can not execute `setup.py` since setuptools is not available in the build environment.
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

我的解决方法是重装setuptools：

pip uninstall setuptools
pip install setuptools

至此，问题一般可以被解决。