IPython import error

[bash-j]

On my IIS server running django 1.10 and plotly 2.0.1, I get the same error as explained in this issue
bokeh/bokeh#5242 , which has been patched in Bokeh.

I have modified the optional_imports.py file similarly to their fix and it also fixed my issue.

Traceback (most recent call last):
  File "...\lib\site-packages\django\core\handlers\exception.py", line 39, in inner
    response = get_response(request)
  File "...\lib\site-packages\django\core\handlers\base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "...\lib\site-packages\django\core\handlers\base.py", line 172, in _get_response
    resolver_match = resolver.resolve(request.path_info)
  File "...\lib\site-packages\django\urls\resolvers.py", line 270, in resolve
    for pattern in self.url_patterns:
  File "...\lib\site-packages\django\utils\functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "...\lib\site-packages\django\urls\resolvers.py", line 313, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "...\lib\site-packages\django\utils\functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "...\lib\site-packages\django\urls\resolvers.py", line 306, in urlconf_module
    return import_module(self.urlconf_name)
  File "...\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "....\urls.py", line 23, in <module>
    from material.frontend import urls as frontend_urls
  File "...\lib\site-packages\material\frontend\urls.py", line 7, in <module>
    url(r'', include(modules.urls)),
  File "...\lib\site-packages\material\frontend\registry.py", line 48, in urls
    patterns.append(module.urls)
  File "...\lib\site-packages\material\frontend\apps.py", line 98, in urls
    return ModuleURLResolver(base_url, self.get_urls(), module=self, app_name=self.label, namespace=self.label)
  File "...\lib\site-packages\material\frontend\apps.py", line 84, in get_urls
    urls_module = import_module(urls_module_name)
  File "...\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "app\urls.py", line 5, in <module>
    from ... import views
  File "app\views.py", line 27, in <module>
    import plotly.offline as py
  File "...\lib\site-packages\plotly\__init__.py", line 31, in <module>
    from plotly import (plotly, graph_objs, grid_objs, tools, utils, session,
  File "...\lib\site-packages\plotly\plotly\__init__.py", line 10, in <module>
    from . plotly import (
  File "...\lib\site-packages\plotly\plotly\plotly.py", line 27, in <module>
    from plotly import exceptions, files, session, tools, utils
  File "...\lib\site-packages\plotly\tools.py", line 59, in <module>
    ipython_core_display = optional_imports.get_module('IPython.core.display')
  File "...\lib\site-packages\plotly\optional_imports.py", line 23, in get_module
    return import_module(name)
  File "...\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "...\lib\site-packages\IPython\__init__.py", line 48, in <module>
    from .core.application import Application
  File "...\lib\site-packages\IPython\core\application.py", line 24, in <module>
    from IPython.core import release, crashhandler
  File "...\lib\site-packages\IPython\core\crashhandler.py", line 28, in <module>
    from IPython.core import ultratb
  File "...\lib\site-packages\IPython\core\ultratb.py", line 111, in <module>
    from IPython.core import debugger
  File "...\lib\site-packages\IPython\core\debugger.py", line 36, in <module>
    from IPython.utils import coloransi, io, py3compat
  File "...\lib\site-packages\IPython\utils\io.py", line 78, in <module>
    stdin = IOStream(sys.stdin, fallback=devnull)
  File "...\lib\site-packages\IPython\utils\io.py", line 36, in __init__
    for meth in filter(clone, dir(stream)):
  File "...\lib\site-packages\IPython\utils\io.py", line 35, in clone
    return not hasattr(self, meth) and not meth.startswith('_')
  File "...\lib\site-packages\IPython\utils\io.py", line 70, in closed
    return self.stream.closed
ValueError: underlying buffer has been detached

[cldougl]

@bash-j can you confirm you're still experiencing this issue in the most recent release (2.0.7)?

[bash-j]

@cldougl still seeing same ValueError after upgrading to 2.0.7. Dropped the patched version of the optional_imports.py file in and all good again.

"""
Stand-alone module to provide information about whether optional deps exist.

"""
from __future__ import absolute_import

from importlib import import_module

import logging

logger = logging.getLogger(__name__)
_not_importable = set()

def get_module(name):
    """
    Return module or None. Absolute import is required.

    :param (str) name: Dot-separated module path. E.g., 'scipy.stats'.
    :raise: (ImportError) Only when exc_msg is defined.
    :return: (module|None) If import succeeds, the module will be returned.

    """
    if name not in _not_importable:
        try:
            return import_module(name)
        except ImportError:
            _not_importable.add(name)
        except Exception:
            _not_importable.add(name)
            msg = "Failed to import optional module `{}`".format(name)
            logger.exception(msg)

[chriddyp]

Reported again here: https://community.plot.ly/t/deploy-dash-on-iis-error/5434

[jonmmease]

This change looks reasonable to me, independent of the details of ipython's interactions with IIS, so I'm fine adding this.

[jonmmease]

Done in #1192 . I know it's been a while, but thanks for reporting and digging into the issue @bash-j!