ModuleNotFoundError: No module named 'selenium'

The selenium package is not installed in the Python running your script. Run python -m pip install selenium and the import works. If it still fails, you installed into a different interpreter than the one running the code, so always use the python -m pip spelling.

The error

ModuleNotFoundError: No module named 'selenium'

Fix it

1. Install selenium with the running interpreter's pip

python -m pip install selenium

Expected: Successfully installed selenium-....

1. Confirm the import

python -c "from selenium import webdriver; print(selenium.__version__ if False else 'ok')"

Expected: prints ok. (The version lives at selenium.__version__ if you need it.)

1. If it still fails, check for a second Python

python --version
pip --version

Expected: both lines reference the same installation. If not, redo step 1 and skip bare pip.

When this applies

• any from selenium import ... fails with ModuleNotFoundError naming selenium
• a new venv, container, or CI runner
• the script worked on another machine

When it does NOT apply

• ImportError: cannot import name 'webdriver' from 'selenium' means a shadowing selenium.py file
• chromedriver PATH errors happen after the import succeeds

Compatibility

selenium 4.x current. Needs Python 3.8+. pip install selenium on Python 2 installs the ancient 3.141 line, which is not what you want.

Why it happens

The package was never installed into the active environment, or it was installed into a different Python. This bites hardest with IDE-managed interpreters and with pip vs pip3 pointing at different installations.

Edge cases

• On Debian/Ubuntu, never apt install python3-selenium and pip install selenium in the same env. Pick one package manager.
• If your project pins selenium in requirements.txt, install the file (pip install -r requirements.txt) rather than the bare package so versions stay consistent.