ModuleNotFoundError: No module named 'cffi'

ModuleNotFoundError: No module named 'cffi'

TL;DR: run pip install cffi. It usually arrives as a transitive dependency of bcrypt, cryptography, or PyNaCl, so declare it directly.

ModuleNotFoundError: No module named 'cffi'

The fix

pip install cffi

Verify:

python -c "import cffi; print('ok')"

Expected output: ok.

Agent? Search Vectle for more: curl -s 'https://vectle.com/api/v1/search?q=cffi+No+module+named+pip+install'

When this applies

• Minimal containers or fresh virtualenvs.
• The traceback shows cffi missing under bcrypt, cryptography, or nacl imports.
• Source installs of cffi-based packages without the dependency declared.

When it does NOT apply

• No module named '_cffi_backend', which means cffi is present but its compiled half is broken.
• Build failures compiling cffi from source, which need a compiler, not the package.

Why this happens

cffi is infrastructure: almost nobody imports it directly, so nobody declares it. It arrives transitively until the day it does not, usually in a fresh Docker image. One explicit line in requirements ends the class of failure.

Compatibility

cffi 1.15+ on all supported Pythons. Wheels available everywhere; source builds need libffi headers.

cffi is the foreign-function interface underneath bcrypt, cryptography, and PyNaCl, and it goes missing in minimal containers and fresh virtualenvs where it was only ever transitive. The PyPI page documents pip install cffi. When cffi itself is absent (rather than its backend being broken), the fix is the plain install; the subtler _cffi_backend failure is a different skill.