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How to solve "ModuleNotFoundError: No module named 'six'" in Python

The error ModuleNotFoundError: No module named 'six' in Python means that the six package is not installed in the Python environment you're using. The six package provides utilities for writing code that's compatible with both Python 2 and Python 3. While Python 2 is no longer supported, some older libraries still depend on six.

This guide shows how to fix this error by installing six.

Understanding the Error​

The ModuleNotFoundError means that when your Python code executes import six, the interpreter can not find a module named six. This almost always means the six package is not installed in the Python environment you're using.

Solution 1: Install six with pip (Most Common)​

The standard way to install six is using pip, Python's package installer:

Basic Installation​

Open your terminal (or command prompt on Windows) and run:

pip install six

Or, if you're sure you're using Python 3:

pip3 install six

Using python -m pip (If pip Isn't in Your PATH)​

If the pip command doesn't work, try:

python -m pip install six  # Use with your system's default Python
python3 -m pip install six # Explicitly use Python 3
  • Using python -m pip ensures that you're using the pip associated with your Python installation.

Windows-Specific Considerations (py launcher)​

On Windows, the py launcher is often helpful:

py -m pip install six

Permissions Issues (sudo or --user)​

On Linux/macOS, you might need sudo for system-wide installation (but virtual environments are strongly preferred):

sudo pip3 install six # System-wide install - use with caution
  • Using sudo installs the package globally.

Alternatively, install into your user's site-packages:

pip install six --user  # Install for the current user only
  • The --user installs packages in your user directory, which doesn't require administrator privileges.

Always use virtual environments for Python projects. They isolate project dependencies and avoid conflicts.

Creating a Virtual Environment​

python3 -m venv venv  # Create an environment named "venv"
# OR: python -m venv venv
# OR: py -m venv venv (Windows)

Activating the Environment​

  • macOS / Linux:

    source venv/bin/activate

  • Windows (Command Prompt):

    venv\Scripts\activate.bat

  • Windows (PowerShell):

    venv\Scripts\Activate.ps1
    • If this doesn't work on Windows (Powershell), you might need to run: 
      Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

After activation, your command prompt shows the environment name (e.g., (venv)). pip install now installs into this environment only.

Installing six Inside the Environment​

With the virtual environment activated:

pip install six  # Installs into the active environment

Troubleshooting​

If you've installed six but still get ModuleNotFoundError:

  • IDE Configuration (VS Code, PyCharm): Your IDE may be using a different interpreter.

    • VS Code: Ctrl+Shift+P (or Cmd+Shift+P on macOS), "Python: Select Interpreter", choose the correct one (your virtual environment).
    • PyCharm: File > Settings > Project > Python Interpreter (or PyCharm > Preferences > Project > Python Interpreter on macOS).

  • Conflicting Installations/Multiple Python Versions: If you have multiple Python versions without using virtual environments, you may have installed six for the wrong one. Use virtual environments to avoid this.

  • Incorrect File/Variable Names: Never name your Python files six.py. This conflicts with the installed library. Similarly, don't create a variable named six before importing the module.

  • Restarting Your IDE/Kernel: Sometimes (especially in Jupyter), you need to restart the kernel or IDE after installation.

  • Reinstalling As a last resort, you may have to reinstall the package:

    pip uninstall six
    pip install six

Using six (Illustrative)​

Once installed, you can import and use six:

import six

# Example (using six.moves for compatibility):
if six.PY2:
    print("Running on Python 2")
else:
    print("Running on Python 3")

print(six.__version__) # Check the installed version

Installing six in Specific Environments​

Anaconda​

conda install -c conda-forge six

Jupyter Notebook​

!pip install six

The exclamation mark executes shell commands in a notebook cell.

Conclusion​

The ModuleNotFoundError: No module named 'six' error is fixed by installing the six package using pip.

  • The best practice is to use a virtual environment for each project to isolate dependencies.
  • If you encounter issues, double-check your IDE's Python interpreter settings and ensure you haven't created conflicting filenames or variable names.

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