Python 3.7.3 虚拟环境中没有名为“_contextvars”的模块

Question

我正在开发 Django 项目，该项目需要 Python3.7.3 虚拟环境 Ubuntu16。所以我创建了一个虚拟环境并在其中安装了所有要求并验证了它，激活了它。

但是当我尝试使用 runserver 运行 Django 服务器时，出现以下错误。

Traceback (most recent call last):
  File "/usr/lib/python3.7/decimal.py", line 3, in <module>
    from _decimal import *
ModuleNotFoundError: No module named '_decimal'

During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File "./interfaces/control/manage.py", line 8, in <module>
        execute_from_command_line(sys.argv)
      File "/home/path/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
        utility.execute()
      File "/home/path/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/home/path/lib/python3.7/site-packages/django/core/management/__init__.py", line 224, in fetch_command
        klass = load_command_class(app_name, subcommand)
      File "/home/path/lib/python3.7/site-packages/django/core/management/__init__.py", line 36, in load_command_class
        module = import_module('%s.management.commands.%s' % (app_name, name))
      File "/home/path/lib/python3.7/importlib/__init__.py", line 127, in import_module
        return _bootstrap._gcd_import(name[level:], package, level)
      File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
      File "<frozen importlib._bootstrap>", line 983, in _find_and_load
      File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
      File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
      File "<frozen importlib._bootstrap_external>", line 728, in exec_module
      File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
      File "/home/path/lib/python3.7/site-packages/django/core/management/commands/runserver.py", line 10, in <module>
        from django.core.servers.basehttp import (
      File "/home/path/lib/python3.7/site-packages/django/core/servers/basehttp.py", line 17, in <module>
        from django.core.handlers.wsgi import LimitedStream
      File "/home/path/lib/python3.7/site-packages/django/core/handlers/wsgi.py", line 8, in <module>
        from django.core.handlers import base
      File "/home/path/lib/python3.7/site-packages/django/core/handlers/base.py", line 7, in <module>
        from django.urls import get_resolver, set_urlconf
      File "/home/path/lib/python3.7/site-packages/django/urls/__init__.py", line 1, in <module>
        from .base import (
      File "/home/path/lib/python3.7/site-packages/django/urls/base.py", line 4, in <module>
        from django.utils.encoding import iri_to_uri
      File "/home/path/lib/python3.7/site-packages/django/utils/encoding.py", line 4, in <module>
        from decimal import Decimal
      File "/usr/lib/python3.7/decimal.py", line 8, in <module>
        from _pydecimal import *
      File "/usr/lib/python3.7/_pydecimal.py", line 436, in <module>
        import contextvars
      File "/usr/lib/python3.7/contextvars.py", line 1, in <module>
        from _contextvars import Context, ContextVar, Token, copy_context
    ModuleNotFoundError: No module named '_contextvars'

注意这里先去我的virtualenv中的Django项目

/home/path/lib/python3.7/site-packages/django/core/management/__init__.py

它再次在此处搜索 python 的全局位置。

/usr/lib/python3.7/_pydecimal.py

谁能告诉我为什么它会转到全局位置并抛出错误。

Answer 1

问题出在全局 Python 解释器本身。

我按照 Installing Python 3.7 on Ubuntu from Source in https://linuxize.com/post/how-to-install-python-3-7-on-ubuntu-18-04/ 安装 Python 3.7.

不知何故，它没有为 python 解释器安装所有必需的包。

如果我使用 Installing Python 3.7 on Ubuntu with Apt.

安装一切正常

Answer 2

在我的例子中，安装在虚拟环境中的 python 版本是 3.7.2，而我电脑中唯一的版本是 3.7.3。所以，我重新安装了 3.7.2 版本，它成功了。希望它对你有用!!!

Answer 3

对我来说，我检查了这个位置，发现我的 requirements.txt 以某种方式将 Werkzeug 更改为 1.5x 版本。所以我恢复了这些更改，解决了我的问题。

试试这个。

pip3 install Werkzeug==2.0.1

Python 3.7.3 虚拟环境中没有名为“_contextvars”的模块

No module named '_contextvars' in Python 3.7.3 virtual environment

python

django

virtualenv

python-3.7

python-contextvars