SSL backend error when using OpenSSL

Question

I was trying to install pycurl in a virtualenv using pip and I got this error

ImportError: pycurl: libcurl link-time ssl backend (openssl) is different from         


        

Answer 1

Reinstallation of curl

I tried every suggestion from this discussion but no one worked for me. As solution I have reinstalled curl and curlib. After that I was able to install pycurl with ssl support inside environment.

At start:

'PycURL/7.43.0 libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32 librtmp/2.3'

Part 1.Re/Installation with pip

Firstly I have removed pycurl from virtualenv using pip as was suggested previous answers:

pip uninstall pycurl
export PYCURL_SSL_LIBRARY=openssl
pip install pycurl --global-option="--with-openssl"

The idea here is that package was cached and we just reintstall it with openssl option.

I also tried to recompile pycurl with pip using:

pip install pycurl --compile pycurl --no-cache

..but had the same error after running:

python
import pycurl
pycurl.version

ImportError: pycurl: libcurl link-time ssl backend (gnutls) is different from compile-time ssl backend (openssl)

Part 2. Installation from tar

After previous method didn't work I have decidede to install pycurl from tar with:

curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
sudo tar -xzvf pycurl-7.43.0.tar.gz
cd pycurl-7.43.0/
sudo python setup.py --with-ssl install

It has installed pycurl globally but not within virtualenv. I also didn't check if it was installed with SSL support or not but think that still without ssl.

Part 3. Reinstallation of curl and curllib

Finally I understood that pycurl doesn't installs normally into environment because global curl and libcurl are compiled with gnutls.

Before starting check it with:

curl-config --configure

One of the output lines will be

'--without-ssl' '--with-gnutls'

To recompile it:

Firstly remove curl:

sudo apt-get purge curl

Install any build dependencies needed for curl

sudo apt-get build-dep curl

Get latest (as of Dec 20, 2016) libcurl

mkdir ~/curl
wget http://curl.haxx.se/download/curl-7.51.0.tar.bz2
tar -xvjf curl-7.51.0.tar.bz2
cd curl-7.51.0

The usual steps for building an app from source

./configure
./make
 sudo make install

If openssl installed correctly then configure will find it automatically. The output will be:

curl version: 7.51.0
Host setup: x86_64-pc-linux-gnu
Install prefix: /usr/local
Compiler: gcc
SSL support: enabled (OpenSSL) ...

Resolve any issues of C-level lib location caches ("shared library cache")

sudo ldconfig

Now try to reinstall pycurl within environment:

curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
pip install pycurl-7.43.0.tar.gz --global-option="--with-openssl"

The result should be:

python
import pycurl
pycurl.version

'PycURL/7.43.0 libcurl/7.51.0 OpenSSL/1.0.2g zlib/1.2.8 librtmp/2.3'