EC
IndentationError
PythonERRORCommonSyntax ErrorHIGH confidence

Incorrect indentation

What this means

Raised when a line of code is not indented correctly. Python uses indentation to define the structure of code blocks, so this is a critical syntax issue.

Why it happens
  1. 1Missing indentation for a code block that requires it (e.g., after an `if` statement).
  2. 2Having inconsistent indentation levels within the same code block.
  3. 3Mixing tabs and spaces for indentation in the same file (a common hidden issue).
How to reproduce

This error occurs when a code block is expected after a statement ending in a colon, but it is not indented.

trigger — this will error
trigger — this will error
def my_function():
print("This line is not indented correctly")

expected output

  File "<stdin>", line 2
    print("This line is not indented correctly")
    ^
IndentationError: expected an indented block

Fix 1

Add proper indentation

WHEN After any line ending with a colon (`:`), such as `def`, `class`, `if`, `for`, `while`.

Add proper indentation
def my_function():
    print("This line is now correctly indented")

Why this works

Indenting the line with four spaces places it inside the `my_function` block, as Python requires.

Fix 2

Configure your editor to use spaces for tabs

WHEN To prevent mixing tabs and spaces, which Python treats as different indentation levels.

Configure your editor to use spaces for tabs
# No code, this is an editor configuration.
# In VS Code, set "editor.insertSpaces": true and "editor.tabSize": 4.

Why this works

This ensures that pressing the Tab key inserts a consistent number of spaces, avoiding `IndentationError` from mixed whitespace.

Code examples
Triggerpython
def foo():
print("oops")  # IndentationError: expected an indented block
Handle with compile()python
try:
    compile("def f():\npass", "<string>", "exec")
except IndentationError as e:
    print(f"Bad indentation at line {e.lineno}")
Avoid with editorconfigpython
# .editorconfig
# [*.py]
# indent_style = space
# indent_size = 4
# Prevents mixed tabs/spaces.
What not to do

✕ Randomly adding or removing spaces until the error disappears

This can lead to incorrect program logic and create further indentation errors elsewhere. Understand why the indentation is required.

Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev

← All Python errors