pip "Missing 'Version:' header and/or METADATA file

表现

pip3 list报错：

➜  ~ pip3 list
/usr/local/bin/pip3:6: UserWarning: Unbuilt egg for Unknown [unknown version] (/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages)
  from pkg_resources import load_entry_point
Exception:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_vendor/pkg_resources/__init__.py", line 2562, in version
    return self._version
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_vendor/pkg_resources/__init__.py", line 2669, in __getattr__
    raise AttributeError(attr)
AttributeError: _version

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/basecommand.py", line 228, in main
    status = self.run(options, args)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/commands/list.py", line 152, in run
    self.output_package_listing(packages, options)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/commands/list.py", line 241, in output_package_listing
    data, header = format_for_columns(packages, options)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/commands/list.py", line 313, in format_for_columns
    row = [proj.project_name, proj.version]
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_vendor/pkg_resources/__init__.py", line 2567, in version
    raise ValueError(tmpl % self.PKG_INFO, self)
ValueError: ("Missing 'Version:' header and/or METADATA file", Unknown [unknown version] (/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages))
You are using pip version 10.0.1, however version 19.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

解决办法

1.让报错更详细些：

2559     @property
2560     def version(self):
2561         try:
2562             return self._version
2563         except AttributeError:
2564             version = _version_from_file(self._get_metadata(self.PKG_INFO))
2565             if version is None:
2566                 # debug0719
2567                 print(self._provider.__dict__)
2568                 tmpl = "Missing 'Version:' header and/or %s file"
2569                 raise ValueError(tmpl % self.PKG_INFO, self)
2570             return version

2.此时，再执行pip3 list，可以看到有问题的文件已被找到：

➜  ~ pip3 list
/usr/local/bin/pip3:6: UserWarning: Unbuilt egg for Unknown [unknown version] (/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages)
  from pkg_resources import load_entry_point
{'module_path': '/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages', 'egg_info': '/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/-equests-2.21.0.dist-info'}
{'module_path': '/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages', 'egg_info': '/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/-equests-2.21.0.dist-info'}
Exception:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_vendor/pkg_resources/__init__.py", line 2562, in version
    return self._version
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_vendor/pkg_resources/__init__.py", line 2671, in __getattr__
    raise AttributeError(attr)
AttributeError: _version

3.删除该报错文件夹即可：

➜  ~ rm -rf /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/-equests-2.21.0.dist-info
➜  ~ pip3 list
Package           Version
----------------- ----------
...

参考资料

https://github.com/pypa/pip/issues/6194