Python pip：ImportError 无法从“six”导入名称“ensure_str”。在多个 pip 命令上

当我第一次想安装 python3 的 tqdm 包时，我注意到出了问题。跑步pip install tqdm我收到了

ImportError: cannot import name 'ensure_str' from 'six' (/home/carl/.local/lib/python3.8/site-packages/six.py).

运行各种 pip 命令时似乎存在类似的问题，例如pip freeze and pip list， 但不是pip show [package] or pip -h.

我不确定从哪里开始以及如何处理这种情况，非常感谢您的帮助。我将在下面发布完整的跟踪以了解上下文。

完整回溯：pip install [any package]

Traceback (most recent call last):
  File "/usr/bin/pip", line 11, in <module>
    load_entry_point('pip==20.0.2', 'console_scripts', 'pip')()
  File "/usr/lib/python3.8/site-packages/pip/_internal/cli/main.py", line 73, in main
    command = create_command(cmd_name, isolated=("--isolated" in cmd_args))
  File "/usr/lib/python3.8/site-packages/pip/_internal/commands/__init__.py", line 96, in create_command
    module = importlib.import_module(module_path)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/lib/python3.8/site-packages/pip/_internal/commands/install.py", line 24, in <module>
    from pip._internal.cli.req_command import RequirementCommand
  File "/usr/lib/python3.8/site-packages/pip/_internal/cli/req_command.py", line 20, in <module>
    from pip._internal.operations.prepare import RequirementPreparer
  File "/usr/lib/python3.8/site-packages/pip/_internal/operations/prepare.py", line 16, in <module>
    from pip._internal.distributions import (
  File "/usr/lib/python3.8/site-packages/pip/_internal/distributions/__init__.py", line 2, in <module>
    from pip._internal.distributions.wheel import WheelDistribution
  File "/usr/lib/python3.8/site-packages/pip/_internal/distributions/wheel.py", line 5, in <module>
    from pip._internal.utils.wheel import pkg_resources_distribution_for_wheel
  File "/usr/lib/python3.8/site-packages/pip/_internal/utils/wheel.py", line 12, in <module>
    from pip._vendor.six import PY2, ensure_str
ImportError: cannot import name 'ensure_str' from 'six' (/home/carl/.local/lib/python3.8/site-packages/six.py) 

追溯：pip freeze

Traceback (most recent call last):
  File "/usr/bin/pip", line 11, in <module>
    load_entry_point('pip==20.0.2', 'console_scripts', 'pip')()
  File "/usr/lib/python3.8/site-packages/pip/_internal/cli/main.py", line 73, in main
    command = create_command(cmd_name, isolated=("--isolated" in cmd_args))
  File "/usr/lib/python3.8/site-packages/pip/_internal/commands/__init__.py", line 96, in create_command
    module = importlib.import_module(module_path)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/lib/python3.8/site-packages/pip/_internal/commands/freeze.py", line 12, in <module>
    from pip._internal.operations.freeze import freeze
  File "/usr/lib/python3.8/site-packages/pip/_internal/operations/freeze.py", line 17, in <module>
    from pip._internal.req.constructors import (
  File "/usr/lib/python3.8/site-packages/pip/_internal/req/__init__.py", line 11, in <module>
    from .req_file import parse_requirements
  File "/usr/lib/python3.8/site-packages/pip/_internal/req/req_file.py", line 25, in <module>
    from pip._internal.req.constructors import (
  File "/usr/lib/python3.8/site-packages/pip/_internal/req/constructors.py", line 28, in <module>
    from pip._internal.req.req_install import InstallRequirement
  File "/usr/lib/python3.8/site-packages/pip/_internal/req/req_install.py", line 30, in <module>
    from pip._internal.operations.install.wheel import install_wheel
  File "/usr/lib/python3.8/site-packages/pip/_internal/operations/install/wheel.py", line 33, in <module>
    from pip._internal.utils.wheel import parse_wheel
  File "/usr/lib/python3.8/site-packages/pip/_internal/utils/wheel.py", line 12, in <module>
    from pip._vendor.six import PY2, ensure_str
ImportError: cannot import name 'ensure_str' from 'six' (/home/carl/.local/lib/python3.8/site-packages/six.py)

EDIT:有人建议我看看https://stackoverflow.com/a/57262415/13516940 https://stackoverflow.com/a/57262415/13516940。它说“ensure_str”包含在六个 1.12 及更高版本中，但我只有 1.11 版本。这就解释了为什么找不到它。但是我无法通过例如运行来解决这个问题pip install --upgrade six nor pip uninstall six or pip check six。因为任何这些命令都会给出相同的“无法导入名称”错误。帮助解决这个问题将不胜感激。

从以下位置安装时，我在虚拟环境中遇到了这个问题requirements.txt代码附带的文件。我的系统 Python (3.8.5) 在我的系统上运行得很好six==1.14.0，但是requirements.txt文件有six==1.11.0。因此，每当我跑步时pip install -r requirements.txt在我的 venv 中，事情会崩溃，因为它会安装旧版本的 6。

我的解决方案是删除我创建的第一个 venv，更改其中的行requirements.txt to six==1.14.0（工作版本），重建我的 venv，然后使用新修改的requirements.txt 文件进行安装。事后看来，这似乎是常识，但当时我并没有想到。简而言之：不要用旧的、不兼容的版本覆盖 6 的工作版本。