title: Error "No module named '_cffi_backend'" when opening cx_Freeze-compiled Python app
body: <p>I'm trying to build my Python up properly for Windows with cx_freeze. The reason I chose this tool is another ones like py2win have issues with newest (for this time: 3.7) python build.</p>
  
  <p>But when I compile the app I cannot start it. I'm getting error:</p>
  
  <blockquote>
  <pre><code>from bcrypt import _bcrypt ModuleNotFoundError: No module named '_cffi_backend'
  </code></pre>
  </blockquote>
  
  <p>I was looking for help at github and stackoverflow. What I did was to reinstall cryptography, paramiko and cffi packages with pip, as described here: <a href="https://stackoverflow.com/questions/34370962/no-module-named-cffi-backend">No module named _cffi_backend</a>. Maybe it's not working for me, because I'm using Python 3 instead of 2. </p>
  
  <p>My setup.py looks like following:</p>
  
  <pre><code>from cx_Freeze import setup, Executable
  import os
  
  os.environ['TCL_LIBRARY'] = r'C:\Users\Kamil\AppData\Local\Programs\Python\Python37-32\tcl\tcl8.6'
  os.environ['TK_LIBRARY'] = r'C:\Users\Kamil\AppData\Local\Programs\Python\Python37-32\tcl\tk8.6'
  
  includes = ["paramiko"]
  
  options =   {
              "includes": includes,
              }
  
  setup(name = 'SIMail',
        version = "0.1",
        description = "SIMail nadzor routerow" ,
        options = {"SIMailGUI.exe" : options},
        executables = [Executable("SIMailGUI.py")])
  </code></pre>
  
  <p>After executing python setup.py build I've got long output with some warnings:</p>
  
  <pre><code>Missing modules:
  ? MySQLdb imported from peewee
  ? StringIO imported from six
  ? UserDict imported from asn1crypto._ordereddict
  ? __builtin__ imported from paramiko.py3compat
  ? __main__ imported from bdb, pdb
  ? _frozen_importlib imported from importlib, importlib.abc
  ? _frozen_importlib_external imported from importlib, importlib._bootstrap, importlib.abc
  ? _posixsubprocess imported from subprocess
  ? _uuid imported from uuid
  ? _winreg imported from platform
  ? cStringIO imported from asn1crypto.core, paramiko.py3compat
  ? collections.Mapping imported from peewee
  ? collections.MutableMapping imported from paramiko.hostkeys
  ? fcntl imported from paramiko.agent
  ? grp imported from shutil, tarfile
  ? gssapi imported from paramiko.ssh_gss
  ? java.lang imported from platform
  ? org.python.core imported from copy, pickle
  ? os.path imported from os, pkgutil, py_compile, tracemalloc, unittest, unittest.util
  ? playhouse._speedups imported from peewee
  ? posix imported from os
  ? psycopg2 imported from peewee
  ? psycopg2cffi imported from peewee
  ? pwd imported from getpass, http.server, posixpath, shutil, tarfile, webbrowser
  ? pymysql imported from peewee
  ? pysqlite2 imported from peewee
  ? pysqlite3 imported from peewee
  ? six.moves imported from cryptography.hazmat.backends.openssl.backend, cryptography.x509.general_name
  ? termios imported from getpass, tty
  ? thread imported from paramiko.win_pageant
  ? urllib.quote imported from asn1crypto._iri
  ? urllib.unquote imported from asn1crypto._iri
  ? urlparse imported from asn1crypto._iri
  ? vms_lib imported from platform
  This is not necessarily a problem - the modules may not be needed on this platform.
  </code></pre>
  
  <p>Full log is pasted here: <a href="https://pastebin.com/SNXdBgnM" rel="nofollow noreferrer">https://pastebin.com/SNXdBgnM</a></p>
  
  <p>Shall I add anything to my setup.py? Do you know how to deal with this problem? I cannot run my app at all.</p>