无法从“pip._internal.models.scheme”导入名称“SCHEME_KEYS”错误

Question

我想在我的虚拟环境中安装flask。我使用“pip installflask”命令，但出现此错误：

raceback (most recent call last):
  File "C:\Users\user\anaconda3\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\user\anaconda3\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\user\Desktop\news_bot\myvenv\Scripts\pip.exe\__main__.py", line 4, in <module>
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\cli\main.py", line 10, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\cli\autocompletion.py", line 9, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\cli\main_parser.py", line 7, in <module>
    from pip._internal.cli import cmdoptions
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\cli\cmdoptions.py", line 24, in <module>
    from pip._internal.cli.progress_bars import BAR_TYPES
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\cli\progress_bars.py", line 12, in <module>
    from pip._internal.utils.logging import get_indentation
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\utils\logging.py", line 18, in <module>
    from pip._internal.utils.misc import ensure_dir
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\utils\misc.py", line 31, in <module>
    from pip._internal.locations import (
  File "c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\locations\__init__.py", line 7, in <module>
    from pip._internal.models.scheme import SCHEME_KEYS, Scheme
ImportError: cannot import name 'SCHEME_KEYS' from 'pip._internal.models.scheme' (c:\users\user\desktop\news_bot\myvenv\lib\site-packages\pip\_internal\models\scheme.py)

我已经更新了 pip，更新后出现此错误。

操作系统：Windows

Python版本：3.8.5

谢谢 ：）

Answer 1

如果您在虚拟环境中工作，则需要将get-pip.py文件保存在anaconda3\Scripts目录中。anaconda3\envs\[env_name]\Scripts

然后，你需要cd到这个目录：

cd anaconda3\Scripts

之后运行：

python get-pip.py pip==19.3.1  # or 21.0.1