No module named _cffi_backend

Question

I have python2.6 in my Linux rhel-5. I have installed pip and required CFFI packages. When i try to run a sample CFFI program it says :

ffi = FFI()

File "/usr/lib/python2.6/site-packages/cffi/api.py", line 56, in init

import _cffi_backend as backend

ImportError: No module named _cffi_backend

what could be the posiible error. Did i miss something during install. i have installed pip, wheel, pycparser, pytest, cffi....

Answer 1

Did you compile Python from source, and if so, did it give you any errors during the configure/make/make install phase? Compiling Python from source can be a real beast on older Red Hat systems, so if you installed that way, I'd suggest combing through the configure and make output to be sure that no modules were left out.

In order to get pip install cffi to succeed with no errors, I had to install gcc and libffi-devel from the EL5 repos. From there, I was able to instantiate an FFI instance with no problems:

>>> from cffi import FFI
>>> ffi = FFI()
>>>

Here's the output of pip freeze, for reference:

[root@machine ~]# pip freeze
argparse==1.2.1
autobahn==0.8.10
cffi==1.5.2
characteristic==14.3.0
pika==0.9.13
pyasn1==0.1.7
pyasn1-modules==0.0.8
pycparser==2.14
pycrypto==2.6.1
pyOpenSSL==0.12
pysnmp==4.2.5
requests==2.7.0
service-identity==14.0.0
six==1.7.3
Twisted==14.0.0
version-utils==0.2.2
wheel==0.24.0
zope.interface==4.1.1

If you've got the same or better versions of the relevant packages installed, I'd try a pip -vvv install --upgrade --force-reinstall cffi, just to see if there are perhaps errors that pip was masking, and go from there.

Answer 2

I encountered this issue when trying to install packages in a local directory using pip install -t . and then running python (2.7). My solution was to remove the -t and not install into a local directory.

Answer 3

I needed to uninstall and install it again:

sudo pip uninstall cryptography

sudo pip uninstall paramiko

then install pagamiko again

sudo pip install paramiko

and it start to work for me

Answer 4

For me there was no way to install cffi on python3.8 because of this:

ImportError: cannot import name 'sysconfig' from 'distutils' (/usr/lib/python3.8/distutils/__init__.py)

Somehow, the package python3-distutils does not exist in Ubuntu 16.04.

So I ended up installing python3.7 and now I finally could install cffi, fixing the problem mentioned by the TS.