No module named _cffi_backend

问题:

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....

回答1:

For python2.x use following command:

python -m pip install cffi

for python3.x

python3 -m pip install cffi

回答2:

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

回答3:

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.

回答4:

Have the same problem. After many attempts adding import cffi solve the issue.

Make sure you have cffi and cryptography installed.

回答5:

You could look at the code L56 in /usr/lib/python2.6/site-packages/cffi/api.py

It needs the _cffi_backend.so in your pythonpath. You could install the python-cffi for it. But not sure whether it is in your RPM repo, especially you are using RHEL-5. Here is an RPM for CENTOS http://cbs.centos.org/koji/rpminfo?rpmID=20613 Hope it helps. I am still searching the source code for building the _cffi_backend.so.

回答6:

I recently had the same issue and none of the above solutions worked for me.

Here is what worked.

sudo apt remove python3-cffi
sudo python3 -m pip install cffi

回答7:

You have to first remove the following packages:

cryptography
bcrypt
paramiko

Now use the following command to install:

pip -vvv install --upgrade --force-reinstall cffi

回答8:

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.

回答9:

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.

回答10:

You should do install cffi pip install cffi to get the latest version. I had to restart my application for it to recognize the cffi installation.