获取“django.core.exceptions.ImproperlyConfigured：需要 GEOS，但尚未检测到”。虽然安装了GEOS

我在跑姜戈 1.8 and Python 3.4 on Ubuntu 14.04 LTS。就在最近，我的 Django 应用程序报告了这一点GEOS不存在。GEOS已安装并且libgeos_c.so是它应该在的地方（/usr/lib/）。我的代码看起来不错。它是仍然有效的 docker 镜像的来源。这似乎表明存在操作系统/不兼容问题。任何帮助将非常感激。

完整的回溯是

Traceback (most recent call last):
  File "<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydevd.py", line 2358, in <module>
    globals = debugger.run(setup['file'], None, None, is_module)
  File "<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydevd.py", line 1778, in run
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc) 
  File "<path/to/my/pycharm/project>/manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/core/management/__init__.py", line 312, in execute
    django.setup()
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models(all_models)
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/apps/config.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python3.4/importlib/__init__.py", line 109, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 2231, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2214, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2203, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 1129, in _exec
  File "<frozen importlib._bootstrap>", line 1448, in exec_module
  File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/auth/models.py", line 41, in <module>
    class Permission(models.Model):
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/models/base.py", line 139, in __new__
    new_class.add_to_class('_meta', Options(meta, **kwargs))
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/models/base.py", line 324, in add_to_class
    value.contribute_to_class(cls, name)
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/models/options.py", line 250, in contribute_to_class
    self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/__init__.py", line 36, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/utils.py", line 240, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/db/utils.py", line 111, in load_backend
    return import_module('%s.base' % backend_name)
  File "/usr/lib/python3.4/importlib/__init__.py", line 109, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 2231, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2214, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2203, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 1129, in _exec
  File "<frozen importlib._bootstrap>", line 1448, in exec_module
  File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/db/backends/postgis/base.py", line 8, in <module>
    from .features import DatabaseFeatures
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/db/backends/postgis/features.py", line 1, in <module>
    from django.contrib.gis.db.backends.base.features import BaseSpatialFeatures
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/db/backends/base/features.py", line 3, in <module>
    from django.contrib.gis.db.models import aggregates
  File "<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/db/models/__init__.py", line 12, in <module>
    "See also https://docs.djangoproject.com/en/%s/ref/contrib/gis/install/geolibs/" % get_docs_version())
django.core.exceptions.ImproperlyConfigured: GEOS is required and has not been detected. Are you sure it is installed? See also https://docs.djangoproject.com/en/1.8/ref/contrib/gis/install/geolibs/

我尝试过重新安装libgdal-dev。所有相关软件包（GDAL、GEOS 等）都是最新的。

我尝试过重新审视 Python 代码。它失败了django/contrib/gis/geos/__init__.py关于以下内容。由于 HAS_GEOS 设置为 false，因此报告 GEOS 不存在。

try:
    from .libgeos import geos_version, geos_version_info  # NOQA: flake8 detects only the last __all__
    HAS_GEOS = True
    __all__ += ['geos_version', 'geos_version_info']
except ImportError:
    HAS_GEOS = False

我怀疑最近的操作系统升级/补丁损坏了 GEOS 或 GDAL。根本原因似乎与ctypes，但我看不出它可能是什么。

以下内容可能有用。

>>> from _ctypes import Union, Structure, Array
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
ImportError: /usr/lib/python3.4/lib-dynload/_ctypes.cpython-34m-x86_64-linux-gnu.so: undefined symbol: _PyTraceback_Add


>>> from django.contrib.gis import gdal
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
  File "/<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/gdal/__init__.py", line 47, in <module>
    from django.contrib.gis.gdal.driver import Driver  # NOQA
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
  File "/<path/to/my/virtualenv>/lib/python3.4/site-packages/django/contrib/gis/gdal/driver.py", line 1, in <module>
    from ctypes import c_void_p
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
  File "/usr/lib/python3.4/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
  File "/<path/to/my/homedir>/pycharm-4.5.1/helpers/pydev/pydev_import_hook.py", line 21, in do_import
    module = self._system_import(name, *args, **kwargs)
ImportError: /usr/lib/python3.4/lib-dynload/_ctypes.cpython-34m-x86_64-linux-gnu.so: undefined symbol: _PyTraceback_Add

我今天遇到了同样的问题，尽管是在一个不相关的 python 项目中。这是我也遇到过的一行，它引导我来到这里：

ImportError: /usr/lib/python3.4/lib-dynload/_ctypes.cpython-34m-x86_64-linux-gnu.so: undefined symbol: _PyTraceback_Add

看起来 Ubunut 已经推送了 Python 3.4 更新，该更新与现有的虚拟环境不兼容。我可以通过重新创建 virtualenv 来解决该问题。目前这不切实际，我只是将 virtualenv 的 python 替换为系统 python：

cd my-virtualenv
cp /usr/bin/python3.4 bin/python3.4

我不能说这是否是一个非常sane要做的事情，但这似乎对我来说确实有效。