升级pip后，它不再工作

Question

我最近更新了我的自制Python 3.8安装。2至3.8。3.做完后，我跑了

$ pip3 install -U pip

以检查是否有任何pip更新。它更新了我从20.0安装的pip。2至20.1。1，并且自从我运行该命令以来，pip在我尝试使用它的任何时候都会抛出一个错误。以下是错误：

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 584, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 901, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 792, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.VersionConflict: (pip 20.1.1 (/usr/local/lib/python3.8/site-packages), Requirement.parse('pip==20.0.2'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/opt/python@3.8/bin/pip3", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3255, in <module>
    def _initialize_master_working_set():
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3238, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3267, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 586, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 599, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 787, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==20.0.2' distribution was not found and is required by the application

升级过程中似乎出现了一些问题，未能更改代码中的版本检查。我看到了类似的问题，但公认的答案对我来说并不适用。如何使pip再次可用？

Answer 1

我在Ubuntu上遇到过类似的问题，下面是我解决问题的方法：

1. 首先通过从OS package manager重新安装来恢复旧版本（可能需要先卸载）

pip3 install --user -U pip

希望这有帮助。

Answer 2

根据Python文档，现在使用pip的正确方法是通过正确的Python可执行文件，例如。

python3-m pip安装-U pip