Ubuntu 20.04 upgrade, Python missing libffi.so.6

I recently upgraded my OS to Ubuntu 20.04 LTS.

Now when I try to import a library like Numpy in Python, I get the following error:

ImportError: libffi.so.6: cannot open shared object file: No such file or directory

I tried installing the libffi package, but apt can't locate it :

sudo apt-get install libffi
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package libffi

If you are using pyenv, you should just uninstall the used python version and then reinstall it.

Example:

pyenv uninstall 3.7.4
pyenv install 3.7.4

It's cleaner and safer than renaming system library from my point of view.

It seems like I fixed it. I could be wrong, but here is what I think happened:

1. Ubuntu 20.04 upgraded libffi6 to libffi7
2. Python is still looking for libffi6

What I did to fix it :

Locate libffi.so.7 in your system

$ find /usr/lib -name "libffi.so*"

Create a simlink named libffi.so.6 that points to libffi.so.7:

sudo ln -s /usr/path/to/libffi.so.7 /usr/lib/path/to/libffi.so.6

UPDATE:

As noted by many users, this fix could have unintended consequences. The better way to do it is to reinstall python as @amichaud explained. This should be used as a last resort IF you're not using pyenv/virtualenv/etc in which case removing python will cause a lot of dependencies to be removed as well.

I am using Xubuntu 20.04 and recompiling the python version 3.7 did not work for me.

The way I solved this was to download the 19.10 version of the package from here: http://mirrors.kernel.org/ubuntu/pool/main/libf/libffi/libffi6_3.2.1-8_amd64.deb

and then installing it

sudo apt install ./libffi6_3.2.1-8_amd64.deb

This will unpack the libffi.so.6 and libffi.so.6.0.4 files to /usr/lib/x86_64-linux-gnu/. The libffi.so.6 file is just a link to libffi.so.6.0.4 in the same directory.

As far as I could see this does not overwrite any files so should be safe.

Hopefully this helps someone as well.

Ubuntu 20 has libffi7 installed instead. It's possible to install the previous version using coming from Ubuntu 19.10 (Eoan Ermine) download from here Or you can follow these commands

$ curl -LO http://archive.ubuntu.com/ubuntu/pool/main/libf/libffi/libffi6_3.2.1-8_amd64.deb

$ sudo dpkg -i libffi6_3.2.1-8_amd64.deb