Troubleshooting pyenv: Python ctypes extension not compiled – Missing libffi lib

What will you learn?

In this comprehensive guide, you will delve into the solution for resolving a common issue encountered during pyenv builds. By addressing the absence of the libffi library required for compiling the Python ctypes extension, you will gain insights into troubleshooting and enhancing your development environment.

Introduction to the Problem and Solution

Encountering the error message “pyenv BUILD FAILED – The Python ctypes extension was not compiled. Missing the libffi lib?” signifies a missing libffi library on your system, leading to compilation challenges with pyenv. To overcome this obstacle, it is essential to install both libffi and its development headers. Once these dependencies are installed, successful Python compilation using pyenv becomes achievable.

When utilizing tools like pyenv to manage multiple Python versions on your machine, ensuring all necessary libraries are present is crucial for seamless builds. Addressing missing dependencies promptly fosters a robust development environment conducive to efficient coding practices.


# Install libffi and its development headers (Linux)
# Select an appropriate package manager for your system if not 'apt-get'
sudo apt-get install libffi-dev

# Reinstall a failed python version using pyenv after installing required libraries
pyenv uninstall <python_version>
pyenv install <python_version>

# Verify by setting the reinstalled version globally or locally
pyenv global <python_version>

# Copyright PHD

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  • Installing Libffi Library: Utilize your system’s package manager (e.g., apt-get for Ubuntu) to install libffi-dev, encompassing both the library and essential headers.

  • Reinstalling Python Version: Post libffi installation, proceed by uninstalling and reinstalling the problematic Python version through pyenv. This ensures compilation occurs with access to all necessary dependencies.

  • Verification: Confirm success by setting the reinstalled version as global or local via pyenv, enabling error checks for any persisting issues.

The outlined resolution process tackles missing dependencies that impede successful builds within a well-managed development environment facilitated by tools like pyenv. By diligently following these steps, users can resume work seamlessly without interruptions from such errors.

  1. How do I determine which version of libffi-dev should be installed?

  2. It is advisable to match your existing libffi version with its corresponding -dev package to ensure compatibility.

  3. Can similar issues arise on macOS or Windows systems?

  4. While this error predominantly affects Unix-based systems due to shared library conventions, analogous solutions may apply in diverse environments.

  5. Does updating pyenv alone rectify dependency problems?

  6. While updating tools like pyenv is vital for enhancements and bug fixes, addressing missing libraries necessitates independent installation steps as elaborated in this guide.

  7. How can I troubleshoot other common build failures associated with pythons via pyevn?

  8. Refer here for insights on implementing ctypes correctly.


Effectively resolving issues linked to absent dependencies such as critical libraries like libffii is paramount for sustaining smooth operations within development environments managed by utilities like pyevn. Adhering rigorously to these troubleshooting steps when confronted with build failures attributed directly towards absent requirements ensures continuous productivity devoid of hindrances caused by compilation errors.

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