title: SFTP Paramiko (Python) - Import Error DLL Load Failed - Not a valid Win32 Application
body: <p>I am a novice Python programmer. I am using a simple paramiko script to download a SFTP file. It started throwing the following error recently: ImportError: DLL load failed: %1 is not a valid Win32 application. It was working for several months without issue. I am using paramiko 2.1.2, cryptography 1.8.1 and Python 2.7.12 32bit on Windows 7 64bit.</p>
  
  <pre><code>&gt;&gt;&gt; t = paramiko.Transport((hostname, port))
  &gt;&gt;&gt; t.connect(username=username, password=password)
  No handlers could be found for logger "paramiko.transport"
  Traceback (most recent call last):
     File "&lt;stdin&gt;", line 1, in &lt;module&gt;
     File "C:\Python27\lib\site-packages\paramiko\transport.py", line 1073, in  connect
        self.start_client()
     File "C:\Python27\lib\site-packages\paramiko\transport.py", line 493, in start_client
        raise e
     ImportError: DLL load failed: %1 is not a valid Win32 application.
  </code></pre>
  
  <p>I have tried to uninstall and reinstall. Rolled back to previous versions, but nothing has resolved this error. I appreciate any help someone can give.</p>
  
  <p>LogFile:</p>
  
  <pre><code>    DEB [20170320-10:23:43.359] thr=1   paramiko.transport: starting thread (client mode): 0x29f2250L
      DEB [20170320-10:23:43.359] thr=1   paramiko.transport: Local version/idstring: SSH-2.0-paramiko_2.1.2
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: Remote version/idstring: SSH-2.0-WS_FTP-SSH_7.7
      INF [20170320-10:23:43.407] thr=1   paramiko.transport: Connected (version 2.0, client WS_FTP-SSH_7.7)
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: kex algos:[u'diffie-hellman-group1-sha1', u'diffie-hellman-group14-sha1'] server key:[u'ssh-dss', u'ssh-rsa'] client encrypt:[u'aes256-ctr', u'aes192-ctr', u'aes128-ctr', u'3des-cbc'] server encrypt:[u'aes256-ctr', u'aes192-ctr', u'aes128-ctr', u'3des-cbc'] client mac:[u'hmac-sha1', u'hmac-sha1-96'] server mac:[u'hmac-sha1', u'hmac-sha1-96'] client compress:[u'none'] server compress:[u'none'] client lang:[u''] server lang:[u''] kex follows?False
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: Kex agreed: diffie-hellman-group1-sha1
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: Cipher agreed: aes128-ctr
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: MAC agreed: hmac-sha1-96
      DEB [20170320-10:23:43.407] thr=1   paramiko.transport: Compression agreed: none
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport: Unknown exception: DLL load failed: %1 is not a valid Win32 application.
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport: Traceback (most recent call last):
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\paramiko\transport.py", line 1783, in run
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     self.kex_engine.parse_next(ptype, m)
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\paramiko\kex_group1.py", line 75, in parse_next
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     return self._parse_kexdh_reply(m)
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\paramiko\kex_group1.py", line 111, in _parse_kexdh_reply
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     self.transport._verify_key(host_key, sig)
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\paramiko\transport.py", line 1628, in _verify_key
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     key = self._key_info[self.host_key_type](Message(host_key))
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\paramiko\rsakey.py", line 59, in __init__
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     ).public_key(default_backend())
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\hazmat\backends\__init__.py", line 74, in default_backend
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     _default_backend = MultiBackend(_available_backends())
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\hazmat\backends\__init__.py", line 31, in _available_backends
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     "cryptography.backends"
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\pkg_resources\__init__.py", line 2308, in resolve
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     module = __import__(self.module_name, fromlist=['__name__'], level=0)
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\hazmat\backends\openssl\__init__.py", line 7, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography.hazmat.backends.openssl.backend import backend
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\hazmat\backends\openssl\backend.py", line 16, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography import utils, x509
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\x509\__init__.py", line 7, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography.x509.base import (
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\x509\base.py", line 16, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography.x509.extensions import Extension, ExtensionType
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\x509\extensions.py", line 19, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography.hazmat.primitives import constant_time, serialization
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:   File "C:\Python27\lib\site-packages\cryptography\hazmat\primitives\constant_time.py", line 9, in &lt;module&gt;
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport:     from cryptography.hazmat.bindings._constant_time import lib
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport: ImportError: DLL load failed: %1 is not a valid Win32 application.
      ERR [20170320-10:23:43.780] thr=1   paramiko.transport: 
  </code></pre>