pip._vendor.pep517.wrappers.backendunavailable误差在安装加密术时

Question

我正在尝试将密码学安装到我的系统中，但是我会收到此错误：

  WARNING: Missing build requirements in pyproject.toml for cryptography from https://files.pythonhosted.org/packages/07/ca/bc827c5e55918ad223d59d299fff92f3563476c3b00d0a9157d9c0217449/cryptography-2.6.1.tar.gz#sha256=26c821cbeb683facb966045e2064303029d572a87ee69ca5a1bf54bf55f93ca6.
  WARNING: The project does not specify a build backend, and pip cannot fall back to setuptools without 'setuptools>=40.8.0' and 'wheel'.
  Getting requirements to build wheel ... done
ERROR: Exception:
Traceback (most recent call last):
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/cli/base_command.py", line 178, in main
    status = self.run(options, args)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 352, in run
    resolver.resolve(requirement_set)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/resolve.py", line 131, in resolve
    self._resolve_one(requirement_set, req)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/resolve.py", line 294, in _resolve_one
    abstract_dist = self._get_abstract_dist_for(req_to_install)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/resolve.py", line 242, in _get_abstract_dist_for
    self.require_hashes
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/operations/prepare.py", line 368, in prepare_linked_requirement
    abstract_dist.prep_for_dist(finder, self.build_isolation)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/operations/prepare.py", line 175, in prep_for_dist
    self.install_backend_dependencies(finder=finder)
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_internal/operations/prepare.py", line 123, in install_backend_dependencies
    reqs = req.pep517_backend.get_requires_for_build_wheel()
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_vendor/pep517/wrappers.py", line 71, in get_requires_for_build_wheel
    'config_settings': config_settings
  File "/data/packages/usr/local/lib/python3.6/site-packages/pip/_vendor/pep517/wrappers.py", line 162, in _call_hook
    raise BackendUnavailable
pip._vendor.pep517.wrappers.BackendUnavailable

这是我的设置：

• Alpine Linux 3.6.2

• python 3.6.3

• pip 19.1

• 车轮0.33.1

• setuptools 41.0.1

知道什么可能是问题，或者如何解决？感谢提前的帮助！

Answer 1

我找不到任何统一的解决方案。您可以尝试以下故障排除步骤。其中一个应该工作。

1. 升级pip版本。

2. 更改库/软件包版本。

3. 如果您是从源安装的，请尝试其他方法。whl软件包或使用tar.gz。

4. 与您的pip install命令一起使用--no-use-pep517(不过对我不起作用，但我认为它适用于某些(。

Answer 2

我在不同的库中遇到了相同的错误，而--no-use-pep517无济于事。但是确实如此：

python -m pip install --upgrade pip