ModuleNotFoundError: No module named 'yaml'

Understanding the Error

ModuleNotFoundError: No module named 'yaml'

This error occurs when you try to import the YAML module in Python, but it hasn't been installed in your environment. The error typically appears when you run code like:

import yaml

Quick Solution

Install PyYAML

The YAML functionality in Python is provided by the PyYAML package. Install it using pip:

pip install pyyaml

Installation Methods

Method 1: Using pip

Standard installation using pip package manager:

pip install pyyaml

For Python 3 specifically:

pip3 install pyyaml

Method 2: Using conda

If you're using Anaconda or Miniconda:

conda install pyyaml

Method 3: Install for specific Python version

If you have multiple Python versions installed:

python3.9 -m pip install pyyaml

Method 4: Install in virtual environment

Best practice: install in a virtual environment:

# Create virtual environment
python -m venv myenv

# Activate (Windows)
myenv\Scripts\activate

# Activate (macOS/Linux)
source myenv/bin/activate

# Install PyYAML
pip install pyyaml

Verify Installation

After installation, verify that PyYAML is correctly installed:

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

You should see the version number printed, for example:

6.0.1

Troubleshooting Common Issues

Issue: Permission Denied

If you get a permission error, try installing with user flag:

pip install --user pyyaml

Issue: Multiple Python Versions

Make sure you're installing to the correct Python version:

# Check which Python you're using
which python
python --version

# Install for that specific version
python -m pip install pyyaml

Issue: IDE Not Recognizing Module

If your IDE still shows the error after installation:

Restart your IDE
Check that your IDE is using the correct Python interpreter
Rebuild your project index (if applicable)
Verify installation in the correct environment

Basic Usage Example

Once installed, you can use PyYAML to work with YAML files:

import yaml

# Load YAML from string
yaml_string = """
name: John Doe
age: 30
skills:
  - Python
  - JavaScript
  - YAML
"""

data = yaml.safe_load(yaml_string)
print(data)

# Write YAML to file
with open('output.yaml', 'w') as file:
    yaml.dump(data, file)