ModuleNotFoundError in Python: How to Fix It Every Time

The Error

ModuleNotFoundError: No module named 'requests'

Python can't find the module you're importing. The fix is almost always one of 6 things.

Cause 1: Package Not Installed

pip install requests
pip show requests

Cause 2: Wrong Virtual Environment

which python     # macOS/Linux
where python     # Windows
pip show requests | grep Location

source venv/bin/activate    # macOS/Linux
venv\Scripts\activate       # Windows

This is the #1 cause of "but I already installed it" confusion.

Cause 3: Python Version Mismatch

python --version
python3.11 -m pip install requests

Always use python -m pip install (not just pip install) to guarantee you install into the Python that will run your code.

Cause 4: Local Module Not Found (Relative Import)

import sys
import os
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

Or install in editable mode:

pip install -e .

Cause 5: Circular Import

Module A imports from Module B, Module B imports from Module A. Fix: move shared code to a third module that neither imports from the others.

##Some packages have different install names vs import names:

• →Pillow → import as PIL
• →scikit-learn → import as sklearn
• →python-dateutil → import as dateutil
• →opencv-python → import as cv2

The Fastest Debug Path

1. pip show <package> — is it installed at all?

2. which python / which pip — same environment?

3. Check for __init__.py if it's a local module

4. Check if install name ≠ import name

With DebugAI, press Ctrl+Shift+P — it reads your import structure and virtual environment context automatically.

→ Install DebugAI