Skip to main content
DevFixHub
Python3 min read2026-03-01

Python IndentationError: unexpected indent

Fix IndentationError and TabError: inconsistent use of tabs and spaces in Python scripts.

Error Code / Stack Trace

IndentationError: unexpected indent / TabError: inconsistent use of tabs and spaces in indentation

Problem Overview

Python code execution halts because the indentation level does not match the preceding block or mixes physical tabs and spaces.

Why Does This Happen?

  • Mixing tabs and spaces in the same source file.
  • Copying code from a website or chat with unexpected whitespace characters.
  • Forgetting to indent the block following an if, for, while, def, or class statement.

Step-by-Step Solution

Step 1: Convert all indentation to 4 spaces

Configure your editor to insert 4 spaces when pressing Tab.

bash
# Automatically reformat files using Black
pip install black
black script.py

Step 2: Inspect whitespace characters

Run Python with the -tt flag to report mixed tabs and spaces.

bash
python3 -m tabnanny script.py

Common Mistakes to Avoid

  • •Using single space or uneven indentation inside the same function block.

Prevention & Best Practices

  • Enable 'Render Whitespace' in VS Code to see dots for spaces and arrows for tabs.

Frequently Asked Questions

Does Python PEP 8 mandate spaces over tabs?

Yes, PEP 8 strictly specifies 4 spaces per indentation level and forbids mixing tabs and spaces.

Related Developer Solutions & Tools

Recommended Tools
Related Error Fixes
In-Depth Tutorials