Fix Python NameError: name 'X' is not defined (2025 Guide)

Posted on: March 19, 2025

Encountered a "NameError: name 'X' is not defined" in Python? This error occurs when you try to use a variable, function, or module that hasn’t been defined or imported. Let’s fix it fast in this 2025 guide!

What Causes "NameError: name 'X' is not defined"?

This error happens when Python can’t find a name (variable, function, etc.) in the current scope. Common causes include:

• Typo in Name: Misspelling a variable or function name (e.g., "prnit" instead of "print").
• Undefined Variable: Using a variable before assigning it a value.
• Missing Import: Forgetting to import a module or function (e.g., using `sqrt` without importing `math`).

Check this demo (run in a Python environment):

# This will trigger "NameError"
print(x)  # x hasn’t been defined yet

Running this throws a NameError because `x` isn’t defined in the code.

How to Fix It: 3 Solutions

Let’s resolve this error with practical steps:

(Diagram: Developer uses undefined name, gets error, defines or imports it, runs successfully.)

Solution 1: Define the Variable

Ensure the variable is assigned a value before use:

# Wrong
print(x)

# Fixed
x = 10
print(x)  # 10

Assign a value to the variable before referencing it.

Solution 2: Correct Typos

Check for spelling mistakes in variable or function names:

# Wrong
prnit("Hello")  # Typo in "print"

# Fixed
print("Hello")  # Correct spelling

Use an IDE with autocompletion to catch typos early.

Solution 3: Import Missing Modules

Import any required modules or functions:

# Wrong
result = sqrt(16)  # sqrt isn’t defined without import

# Fixed
from math import sqrt
result = sqrt(16)  # 4.0

Add the necessary `import` statement at the top of your script.

Quick Checklist

• Variable undefined? (Assign it first)
• Name misspelled? (Double-check spelling)
• Module missing? (Import it)

Conclusion

The "NameError: name 'X' is not defined" in Python is a simple but common issue that can be fixed by defining variables, correcting typos, or importing modules. With these 2025 solutions, you’ll debug faster. Got another Python error? Let us know in the comments!