How do I install flask in Python?

The standard way to install flask is by running `python -m pip install flask`. If you are using Anaconda, use `conda install -c conda-forge flask`.

Why causes the 'No module named flask' error?

This error occurs when the python interpreter cannot locate the `flask` package. It is often caused by missing installation or environment mismatch (e.g. installing in global but running in venv).

How to fix ModuleNotFoundError: No module named 'flask'

ModuleNotFoundError: No module named 'flask'

For web development, always isolate your dependencies in a virtual environment.

Using Docker? Ensure you add `flask` to your `requirements.txt` and rebuild the container.

python -m pip install flask

Verification

Command

python -c "import flask; print(flask.__version__)"

Expected output

Success! flask version x.y.z (e.g., 2.4.0)