python -m pip install --upgrade pip

Exception:

Traceback (most recent call last):

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\cli\base_command.py", line 179, in main

    status = self.run(options, args)

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\commands\install.py", line 384, in run

    installed = install_given_reqs(

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\req\__init__.py", line 53, in install_given_reqs

    requirement.install(

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\req\req_install.py", line 910, in install

    self.move_wheel_files(

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\req\req_install.py", line 437, in move_wheel_files

    move_wheel_files(

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_internal\wheel.py", line 544, in move_wheel_files

    generated.extend(maker.make(spec))

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_vendor\distlib\scripts.py", line 405, in make

    self._make_script(entry, filenames, options=options)

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_vendor\distlib\scripts.py", line 309, in _make_script

    self._write_script(scriptnames, shebang, script, filenames, ext)

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_vendor\distlib\scripts.py", line 245, in _write_script

    launcher = self._get_launcher('t')

  File "D:\Python3\lib\site-packages\pip-19.0.3-py3.8.egg\pip\_vendor\distlib\scripts.py", line 384, in _get_launcher

    result = finder(distlib_package).find(name).bytes

AttributeError: 'NoneType' object has no attribute 'bytes'

方法二

pip install lxml‑4.3.1‑cp34‑cp34m‑win_amd64.whl

​lxml?4.3.1?cp34?cp34m?win_amd64.whl is not a valid wheel filename.