ModuleNotFoundError: No module named 'black'

TL;DR

Run python -m pip install black. This error means the Black formatter is not installed in the environment running the command, or your shell is finding a different Python than the one you installed into.

ModuleNotFoundError: No module named 'black'

Fix it

1. Install it. Run python -m pip install black.

   • Expected: Successfully installed black-....

2. Verify. Run black --version.

   • Expected: black, version ....
3. If it still fails, check which black and which python point at the same environment.

When this applies

• Fresh machine, new virtualenv, or CI job missing the formatter.
• pre-commit hook environment issues (see the hook's own troubleshooting).

When it does not apply

• If black runs but crashes on a file, that is a parsing or config issue.

Tool compatibility

black 23.x/24.x, Python 3.8+. pip install black.

Why it happens

black the command comes from the black package. No package, no command, and python -m black fails the same way.

Edge cases

• For blackd (the daemon), you need the d extra: pip install "black[d]", which pulls in aiohttp.