I have this issue in Bionic. It was caused by pip using an old install of an obsolete cffi in ~/.local from a pip --user install, as explained (and diagnosed) here:
https://stackoverflow.com/q/54054263/507544
I have this issue in Bionic. It was caused by pip using an old install of an obsolete cffi in ~/.local from a pip --user install, as explained (and diagnosed) here:
https:/ /stackoverflow. com/q/54054263/ 507544