IndentationError

IndentationError is a subclass of SyntaxError raised when Python encounters incorrect indentation. Since Python uses indentation to define code blocks, inconsistent or missing indentation prevents the code from being parsed.

Common causes

• Mixing tabs and spaces for indentation
• Missing indentation after colon (if, for, def, class)
• Extra or unexpected indentation
• Inconsistent indentation levels within a block
• Copy-pasting code from different sources with mixed whitespace

How to fix it

• Configure your editor to use spaces only (4 spaces per level)
• Use "Show Whitespace" in your editor to visualize tabs vs spaces
• Run python -tt script.py to detect tab/space mixing
• Use autopep8 or black to auto-format indentation
• Re-indent the affected block consistently

Example

# Error example
def greet(name):
print(f"Hello, {name}")  # IndentationError: expected an indented block

if True:
    print("yes")
  print("maybe")  # IndentationError: unexpected indent

# Fix: consistent 4-space indentation
def greet(name):
    print(f"Hello, {name}")

if True:
    print("yes")
    print("maybe")

Related errors