Name Error
Quick summary
You referenced a name (variable, function, class) that doesn't exist in the current scope.
Why this happens
Typo in the variable or function name
Forgot to define or import the name before using it
Used a variable outside its scope (e.g., a local variable outside its function)
Minimal example
print(count)count = 0
print(count)count is never assigned a value before it is used — define it first.
How to diagnose
Check the spelling of the name against its definition
Verify the name is defined or imported before the line that uses it
Check the scope — is the name visible where you're using it?
How to fix
Fix the typo to match the defined name
Define or import the name before using it
Move the code into the correct scope or make the name accessible
How to prevent
Use an IDE with autocomplete to avoid typos
Enable linters that catch undefined names (ESLint
no-undef, flake8)
Related Resources
Related Lessons
- Variables
Learn how variables work in programming
Related Practice
- Variable Declaration Quiz
Test your understanding of variable declaration.
- Declare a Constant Practice
Practice declaring variables.