Pin Dependencies to Avoid pip Install Failures
On Raspbian 11 (Bullseye) running on armv7l, installing Certbot via pip under Python 3.9 can fail due to build and dependency compatibility issues. A practical workaround is to pin versions explicitly so pip resolves a known-good combination. In particular, locking cffi to a compatible release helps prevent compilation or wheel resolution errors that block Certbot installation.
Use the following approach to proceed reliably:
pip install "cffi<2.0.0" certbot- Pin
cffito a specific version known to work on armv7l - Install a matching Certbot version in the same command
- Prefer a clean virtual environment to avoid conflicting packages
- Re-run with
--no-cache-dirif you suspect cached artifacts - Verify the installed versions after completion
Alternative: Install libffi-dev to Build Newer cffi
As an alternative approach, you can install the system development package for libffi so that cffi==2.0.0 can be built/installed successfully even on armv7l environments.
sudo apt update
sudo apt install -y libffi-dev
pip install "cffi==2.0.0"If you still encounter build-related issues, also ensure basic build tooling is present (e.g., build-essential and Python headers), and retry with --no-cache-dir.
This version-pinning strategy provides a stable path to install Certbot on constrained ARM environments without changing the OS or Python version.