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trying to run a pymodbus tcp server and im getting this stack trace... at a total loss here so any help is appreciated. Thanks!

Traceback (most recent call last):
File "Worrking_ModbusJ1939Bridge.py", line 12, in <module>
from pymodbus.server.async import StartTcpServer
File "build/bdist.linux-armv7l/egg/pymodbus/server/async.py", line 18, in <module>
File "build/bdist.linux-armv7l/egg/pymodbus/internal/ptwisted.py", line 5, in <module>
File "/usr/local/lib/python2.7/dist-packages/twisted/conch/manhole_ssh.py", line 14, in <module>
from twisted.conch.ssh import factory, session
File "/usr/local/lib/python2.7/dist-packages/twisted/conch/ssh/factory.py", line 18, in <module>
from twisted.conch.ssh import (_kex, transport, userauth, connection)
File "/usr/local/lib/python2.7/dist packages/twisted/conch/ssh/transport.py", line 345, in <module>
class SSHTransportBase(protocol.Protocol):
File "/usr/local/lib/python2.7/dist-packages/twisted/conch/ssh/transport.py", line 469, in SSHTransportBase
supportedCiphers = _getSupportedCiphers()
File "/usr/local/lib/python2.7/dist-packages/twisted/conch/ssh/transport.py", line 335, in _getSupportedCiphers
backend=default_backend(),
File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/__init__.py", line 15, in default_backend
from cryptography.hazmat.backends.openssl.backend import backend
File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/__init__.py", line 7, in <module>
from cryptography.hazmat.backends.openssl.backend import backend
File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/backend.py", line 16, in <module>
from cryptography import utils, x509
File "/usr/local/lib/python2.7/dist-packages/cryptography/x509/__init__.py", line 7, in <module>
from cryptography.x509 import certificate_transparency
ImportError: cannot import name certificate_transparency
I was using pip 7 and got the same problem. Upgrading to pip 9 solved it. I'm not sure about the cause.
Via: https://github.com/micheloosterhof/cowrie/issues/618
I've been hitting this while attempting to update Python Cryptography for Solaris 11.4, using the https://github.com/oracle/solaris-userland/ build system. A "simple" update to pip isn't an option for me, that's not how we do things.
I eventually figured out the solution: I'd built the package incorrectly.
Cryptography 2.1.4 depends on cffi > 1.7. Both of these packages have new deliverable bits compared to the versions we were shipping. 
Failing to update the package manifest to correctly track the new files results in both cffi and cryptography being unable to import symbols that the current versions depend upon.
[A very big thankyou to Alex Gaynor in #cryptography-dev who set me on the right path to figuring this out].
$ python2.7   
Python 2.7.14 (default, Jan 31 2018, 05:35:05) [C] on sunos5
Type "help", "copyright", "credits" or "license" for more information.
>>> from cryptography.hazmat.bindings._openssl import ffi, lib
>>> from cryptography.x509 import certificate_transparency
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/vendor-packages/cryptography/x509/__init__.py", line 7, in <module>
    from cryptography.x509 import certificate_transparency
ImportError: cannot import name certificate_transparency
If you build cryptography and look at what it delivers, you will find that there is in fact a file (shipped on Solaris as /usr/lib/python-$(PYVER)/vendor-packages/cryptography/x509/certificate_transparency.py) - and if that file isn't in the rest of the hierarchy then you end up with exactly this ImportError.
                Please add a minimal explanation in the answer itself, as the link provided may happen to unavailable in the future.
– n4m31ess_c0d3r
                Apr 3, 2018 at 12:33
I had a similar issue on RHEL 6.7 x86_64 running Python 2.7.8 with an old version of pip (1.4.1)
It was because I had been installing the "cp27m" builds rather than "cp27mu" builds.
With the old pip 1.4.1 build, it did not complain installing the cp27m builds.
Whereas when upgrading pip to 9.0.3, it spat out the true error ... 
(bmcs2)bash-4.1$ pip install cffi-1.11.5-cp27-cp27m-manylinux1_x86_64.whl
cffi-1.11.5-cp27-cp27m-manylinux1_x86_64.whl is not a supported wheel on this platform.
(bmcs2)bash-4.1$ pip install cryptography-2.1.3-cp27-cp27m-manylinux1_x86_64.whl
cryptography-2.1.3-cp27-cp27m-manylinux1_x86_64.whl is not a supported wheel on this platform.
The "ImportError: cannot import name certificate_transparency" was resolved using the "cp27mu" builds.  When using the "cp27mu" build, both the pip 1.4.1 and pip 9.0.3 versions worked fine.
cffi-1.11.5-cp27-cp27m-manylinux1_x86_64.whl versus cffi-1.11.5-cp27-cp27mu-manylinux1_x86_64.whl
cryptography-2.1.3-cp27-cp27m-manylinux1_x86_64.whl versus cryptography-2.1.3-cp27-cp27mu-manylinux1_i686.whl
More info here: 
https://www.python.org/dev/peps/pep-0513/#ucs-2-vs-ucs-4-builds
I think this more like a paramiko issue not pip. Upgrading pip didn't solve this in my environment i had to downgrade my paramiko version to a version that does not have a libffi dependency, this worked for me:  
pip2.7 install paramiko==1.17.0
this issue is related to: https://github.com/paramiko/paramiko/issues/1401
I got this error while trying to run Scrapy in AWS Lambda, deploying with a zip file.
I followed the instructions in https://www.perrygeo.com/running-python-with-compiled-code-on-aws-lambda.html, which basically instructs you to start an Amazon Linux EC2 instance, install the requirements and build the zip from it.
After setting up the whole thing, the first package I created still gave me the same error, but I realised that was because a hidden folder, .libs_cffi_backend, was missing from the zip file. That folder contains a .so file that if not present causes ImportError. After forcefully including it, it worked.
        
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