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

The error ModuleNotFoundError: No module named 'lxml' means that Python can not find the lxml library. lxml is a powerful and feature-rich library for processing XML and HTML in Python. This error almost always means you haven't installed it, or you've installed it in the wrong Python environment.

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

Understanding the Error​

The ModuleNotFoundError is a very common Python error. It means your Python code is trying to import lxml, but the Python interpreter can't find a package named lxml in any of the locations it searches for installed packages.

Solution 1: Install lxml with pip (in a Virtual Environment!)​

The best practice and strongly recommended approach is to use a virtual environment. This keeps your project's dependencies isolated.

  • Step 1: Create a Virtual Environment (if you don't have one):

    python3 -m venv venv  # Or: python -m venv venv  ,  or: py -m venv venv

    This creates a directory named venv (you can use any name) that contains a self-contained Python environment.

  • Step 2: Activate the Virtual Environment:

    • macOS / Linux:

      source venv/bin/activate

    • Windows (Command Prompt):

      venv\Scripts\activate.bat

    • Windows (PowerShell):

      venv\Scripts\Activate.ps1
      • If you get a "running scripts is disabled" error in PowerShell, you may need to temporarily change the execution policy: 
        Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
      • Then run venv\Scripts\Activate.ps1 again.

    After activation, your command prompt should show (venv) (or whatever you named your environment) at the beginning of the line.

  • Step 3: Install lxml:

    pip install lxml
    note

    If pip doesn't work, try these:

    pip3 install lxml # If pip is mapped to Python2
    python -m pip install lxml # Use the python executable
    python3 -m pip install lxml
    py -m pip install lxml  # Windows Python launcher
    • If you encounter a permissions error, try pip install lxml --user (though this is less desirable than using a virtual environment).

Troubleshooting​

If you're still getting the error after installing lxml, consider these possibilities:

Virtual Environment Activation​

Make absolutely sure your virtual environment is activated. The command prompt should show the environment name (e.g., (venv)). If it doesn't, you're installing into the global environment, which is what you're trying to avoid.

IDE Configuration (VS Code, PyCharm)​

Your IDE (like VS Code or PyCharm) might be using a different Python interpreter than your terminal.

  • VS Code: Press Ctrl+Shift+P (or Cmd+Shift+P on macOS), type "Python: Select Interpreter", and choose the interpreter within your virtual environment (it will usually have the environment name in the path).
  • PyCharm: Go to File > Settings > Project > Python Interpreter (or PyCharm > Preferences > Project > Python Interpreter on macOS) and select the correct interpreter (your virtual environment).

Conflicting Installations / Multiple Python Versions​

If you have multiple Python versions installed without using virtual environments, you could have installed lxml for the wrong one. Always use virtual environments to avoid this.

Incorrect Filenames/Variable Names​

Never name your Python files lxml.py. This will conflict with the installed library. Also, avoid creating variables named lxml before you import the module.

Restarting Your IDE/Kernel​

Sometimes, especially in interactive environments like Jupyter notebooks, or after installing a new package, you need to restart the Python kernel or the entire IDE for the changes to take effect.

Reinstalling​

If none of the above steps help, try uninstalling and reinstalling the package, to make sure there are no corrupted files.

pip uninstall lxml
pip install lxml

Using lxml (Example)​

Once lxml is installed correctly, you can import and use it:

from lxml import etree

html_string = """
<div>
  <ul>
    <li>tutorial</li>
    <li>reference</li>
    <li>com</li>
  </ul>
</div>
"""

result = etree.fromstring(html_string).text_content()

print(result)

Output:

tutorial
reference
com

Installing lxml in Specific Environments​

Anaconda​

conda install -c anaconda lxml

Jupyter Notebook​

Within a notebook cell:

!pip install lxml

Conclusion​

The ModuleNotFoundError: No module named 'lxml' error is almost always resolved by installing the lxml package using pip, preferably within a virtual environment. If problems persist, check your IDE's Python interpreter, ensure you're using the correct virtual environment, and avoid filename conflicts.

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