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How to Solve "ModuleNotFoundError: No module named 'pytz'" in Python

The error ModuleNotFoundError: No module named 'pytz' in Python means that the pytz library, which provides timezone definitions, is not installed in your current Python environment.

This guide provides a step-by-step guide to installing pytz and resolving this common error.

Understanding the Error​

The ModuleNotFoundError indicates that Python can not find a module named pytz when your code tries to import pytz or from pytz import .... This usually means the package is not installed in the Python environment you're using.

The standard way to install Python packages is using pip.

Basic Installation​

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

pip install pytz

If you have multiple Python versions installed, or if pip is associated with Python 2, use:

pip3 install pytz # Use pip3 for Python 3 (might be pip3.x)

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

If the pip command doesn't work (e.g., "command not found"), use this instead:

python -m pip install pytz  # Use with your system's default Python
python3 -m pip install pytz # Use with your system's Python 3
  • This ensures 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 pytz
  • The py command uses the latest Python version installed.

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 pytz # System-wide. Use with caution.

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

pip install pytz --user # Install for current user only
  • Use sudo to install packages globally.
  • The --user installs packages in your user directory, which doesn't require administrator privileges.

Always use virtual environments for Python projects to isolate dependencies:

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 fails in PowerShell, you may need to adjust the execution policy: 
      Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
      Then run venv\Scripts\Activate.ps1 again.

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

Installing pytz Inside the Environment​

With your virtual environment activated:

pip install pytz  # Installs into the active environment

Troubleshooting​

If you're still getting the error after installing:

  • IDE Configuration (VS Code, PyCharm): Your IDE might be using a different Python interpreter.
    • VS Code: Press Ctrl+Shift+P (or Cmd+Shift+P on macOS), type "Python: Select Interpreter", and choose the correct interpreter (your virtual environment).
    • PyCharm: File > Settings > Project > Python Interpreter (or PyCharm > Preferences > Project > Python Interpreter on macOS), select the correct interpreter.
  • Conflicting Installations/Multiple Python Versions: If you have multiple Python versions without using virtual environments, you may have installed pytz for the wrong version. Always use virtual environments!
  • Incorrect Filenames/Variable Names: Never name your Python files pytz.py. This conflicts with the installed library. Avoid variable names like pytz as well.
  • Restarting Your IDE/Kernel: Sometimes (especially in Jupyter), you need to restart.
  • Reinstalling Pytz As a last resort, you can try reinstalling the package, as it might resolve any issues that might be cause by incorrect or partial installations:
# First uninstall
pip uninstall pytz
# Then install again
pip install pytz

Using pytz (Example)​

Once installed, you can use pytz:

from pytz import timezone
import pytz

utc = pytz.utc
print(utc.zone)  # Output: UTC

eastern = timezone('US/Eastern')
print(eastern.zone) # Output: US/Eastern

Installing pytz in Specific Environments​

Anaconda​

conda install -c conda-forge pytz

Jupyter Notebook​

Within a notebook cell:

!pip install pytz
  • The ! character allows running shell commands inside Jupyter.

Conclusion​

The ModuleNotFoundError: No module named 'pytz' error is fixed by installing the pytz package, preferably within a virtual environment.

If you encounter problems, double-check:

  • Your IDE settings.
  • Ensure you're using the correct virtual environment.
  • Avoid filename/variable name conflicts.

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