Comment 4 for bug 1512792

Starting LSB: Calendar and Contacts Server...
 calendarserver[2071]: Unhandled Error
 calendarserver[2071]: Traceback (most recent call last):
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 579,
 calendarserver[2071]: usage.Options.parseOptions(self, options)
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/python/usage.py", line 262, in
 calendarserver[2071]: for (cmd, short, parser, doc) in self.subCommands:
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/application/app.py", line 596,
 calendarserver[2071]: for plug in sorted(plugins, key=attrgetter('tapname')):
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/plugin.py", line 213, in getPl
 calendarserver[2071]: allDropins = getCache(package)
 calendarserver[2071]: --- <exception caught here> ---
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/plugin.py", line 171, in getCa
 calendarserver[2071]: provider = pluginModule.load()
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/python/modules.py", line 389,
 calendarserver[2071]: return self.pathEntry.pythonPath.moduleLoader(self.name)
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/python/reflect.py", line 303,
 calendarserver[2071]: topLevelPackage = _importAndCheckStack(trialname)
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/python/reflect.py", line 242,
 calendarserver[2071]: return __import__(importName)
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/plugins/twisted_core.py", line
 calendarserver[2071]: from twisted.internet.endpoints import (
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/internet/endpoints.py", line 4
 calendarserver[2071]: from twisted.protocols.tls import TLSMemoryBIOFactory
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/twisted/protocols/tls.py", line 41, in
 calendarserver[2071]: from OpenSSL.SSL import Error, ZeroReturnError, WantReadError
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/OpenSSL/__init__.py", line 8, in <modu
 calendarserver[2071]: from OpenSSL import rand, crypto, SSL
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/OpenSSL/rand.py", line 11, in <module>
 calendarserver[2071]: from OpenSSL._util import (
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/OpenSSL/_util.py", line 6, in <module>
 calendarserver[2071]: from cryptography.hazmat.bindings.openssl.binding import Binding
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/bindings/openssl/b
 calendarserver[2071]: error=-1)
 calendarserver[2071]: File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/bindings/openssl/b
 calendarserver[2071]: ffi.def_extern(name=name, **kwargs)(func)
 calendarserver[2071]: exceptions.AttributeError: 'CompiledFFI' object has no attribute 'def_extern'

My configuration :

Ubuntu 16.04 LTS 64 bit

 uname -a
Linux mparchet--4.4.0-22-generic #39-Ubuntu SMP Thu May 5 16:53:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

sudo easy_install -U cffiTraceback (most recent call last):
  File "/usr/bin/easy_install", line 9, in <module>
    load_entry_point('setuptools==20.7.0', 'console_scripts', 'easy_install')()
  File "/home/mparchet/.local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 552, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/home/mparchet/.local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2672, in load_entry_point
    return ep.load()
  File "/home/mparchet/.local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2345, in load
    return self.resolve()
  File "/home/mparchet/.local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2351, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/lib/python2.7/dist-packages/setuptools/__init__.py", line 11, in <module>
    from setuptools.extern.six.moves import filterfalse, map
  File "/usr/lib/python2.7/dist-packages/setuptools/extern/__init__.py", line 1, in <module>
    from pkg_resources.extern import VendorImporter
ImportError: No module named extern

 sudo apt-cache policy calendarserver
calendarserver:
  Installed: 7.0+dfsg-2
  Candidate: 7.0+dfsg-2
  Version table:
 *** 7.0+dfsg-2 500
        500 http://ch.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        100 /var/lib/dpkg/status

Could you help me plsease to fix this issues ?

Best regards

Battant