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Python4 min read2026-03-01

Python ModuleNotFoundError: No module named 'xyz'

Fix ModuleNotFoundError: No module named in Python virtual environments and scripts.

Error Code / Stack Trace

ModuleNotFoundError: No module named 'requests'

Problem Overview

Python interpreter cannot find the imported library in the active sys.path or site-packages directory.

Why Does This Happen?

  • The package was installed in a different Python version or virtual environment than the one executing the script.
  • The virtual environment is not activated in the terminal.
  • The script filename collides with the module name (e.g. naming your file requests.py).

Step-by-Step Solution

Step 1: Check active Python interpreter and install package

Ensure pip is executing for the exact Python binary running your script.

bash
python3 -m pip install requests

Step 2: Verify virtual environment activation

Activate your project virtual environment before running code.

bash
source venv/bin/activate
# On Windows: venv\Scripts\activate
python app.py

Common Mistakes to Avoid

  • •Running 'pip install' without realizing pip points to system Python 3.9 while the IDE is running Python 3.12.
  • •Naming a local script email.py, math.py, or requests.py, shadowing the standard library.

Prevention & Best Practices

  • Always run 'python -m pip install' to guarantee packages are installed to the active interpreter.

Frequently Asked Questions

How do I check which Python environment is active?

Run 'which python' (macOS/Linux) or 'where python' (Windows), or print sys.executable inside Python.

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