Workaround for Certbot Installation on Raspbian 11 (Bullseye) armv7l with Python 3.9

Source: Dev.to

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 cffi to 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-dir if you suspect cached artifacts
• Verify the installed versions after completion

Alternative: Install libffi-dev to Build Newer cffi

As an alternative, 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, 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.