ModuleNotFoundError: No module named ‘xyz’

The error message:

ModuleNotFoundError: No module named 'xyz'

occurs when Python cannot find the module xyz because:

1. The module is not installed.
2. The module name is misspelled.
3. The module is not in the correct environment.
4. There is a conflict with another file name in the project.

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1. Causes and Solutions

Cause 1: The Module is Not Installed

If the module is an external package (like numpy, pandas, etc.), it must be installed separately.

Incorrect Code:

import numpy  # If 'numpy' is not installed

Error Output:

ModuleNotFoundError: No module named 'numpy'

Solution: Install the Missing Module

Run the following command in the terminal or command prompt:

pip install numpy

If using Jupyter Notebook, run:

!pip install numpy

If using conda, run:

conda install numpy

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Cause 2: Incorrect Module Name or Typo

Python module names are case-sensitive and should be spelled correctly.

Incorrect Code:

import Pandas  # Wrong capitalization

Error Output:

ModuleNotFoundError: No module named 'Pandas'

Solution: Use the Correct Module Name

import pandas  # Correct spelling and case

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Cause 3: Using the Wrong Python Environment

If a package is installed in a different Python environment, Python cannot find it.

Solution: Check Your Python Version and Environment

1. Check the Python version where the module is installed: python -m pip show numpy
2. If you are using a virtual environment, activate it first: source venv/bin/activate # macOS/Linux venv\Scripts\activate # Windows Then install the package: shCopyEditpip install numpy

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Cause 4: The Module is Not in the Correct Directory

If you created a custom module (xyz.py), Python must know where to find it.

Incorrect Code:

import mymodule  # If 'mymodule.py' is not in the project folder

Solution: Add the Module Path

import sys
sys.path.append('/path/to/module')  # Add the correct path
import mymodule

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Cause 5: File Name Conflict

If your script is named the same as a module, Python might import your script instead.

Incorrect Scenario:

• Your file is named math.py.
• You try to import Python’s built-in math module.
• Python loads your math.py file instead, causing an error.

Solution: Rename Your Script

• Rename math.py to something else, like math_util.py.
• Delete any __pycache__ folders.

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2. Best Practices to Avoid ModuleNotFoundError

Install missing modules using pip install module_name
Use the correct spelling and capitalization
Check your Python environment and virtual environments
Avoid naming files the same as modules
Use sys.path.append() if importing a custom module