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March 25, 2026 - “The NameError exception occurs if you use a variable that is not defined.” — W3Schools, 2024 Source link · Python's case sensitivity makes even subtle differences problematic.

January 8, 2024 - NameError is a kind of error in Python that occurs when executing a function, variable, library, or string without quotes that have been typed in the code without any previous Declaration.

July 1, 2026 - Traceback (most recent call last): File "<main.py>", line 1, in <module> NameError: name 'user_name' is not defined · Explanation: user_name has not been defined anywhere in the program.

NameError is a built-in exception that occurs when you try to use a variable or function name that isn’t defined yet.

NameError exceptions in Python are generally raised when you try to access a variable that you have not defined properly. This could happen because the variable truly hasn't been defined yet, or perhaps only be due to a slight typo.

November 24, 2024 - In summary, NameError in Python occurs when you try to use a variable or function name that has not been defined yet or is out of scope.

Traceback (most recent call last): File "demo_list_del2.py", line 3, in <module> print(thislist) #this will cause an error because you have succsesfully deleted "thislist". NameError: name 'thislist' is not defined

March 6, 2024 - In technical terms, this error is raised when your code refers to a name that hasn't been defined yet. It's Python's way of saying, "I don't know what you're talking about!" One of the most common causes for a NameError is simply misspelling ...

December 1, 2023 - A NameError is raised when you try to use a variable or a function name that is not valid. In Python, code runs from top to bottom. This means that you cannot declare a variable after you try to use it in your code.

>>> 10 * (1/0) Traceback (most recent call last): File "<stdin>", line 1, in <module> 10 * (1/0) ~^~ ZeroDivisionError: division by zero >>> 4 + spam*3 Traceback (most recent call last): File "<stdin>", line 1, in <module> 4 + spam*3 ^^^^ NameError: name 'spam' is not defined >>> '2' + 2 Traceback (most recent call last): File "<stdin>", line 1, in <module> '2' + 2 ~~~~^~~ TypeError: can only concatenate str (not "int") to str

September 28, 2021 - The code above raised an error because line 3 is missing the closing parenthesis. You will encounter a nameerror ( name is not defined) when a variable is not defined in the local or global scope.

I tried the coding example the book told me to try, but I get this NameError that I do not understand why it is an error. ... CopyFile "/Users/eric/Python Notes/Notes.py", line 1, in <module> name = input('What is your name?\n') File "<string>", line 1, in <module> NameError: name 'eric' is not defined

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This tutorial will guide you through understanding the NameError, identifying its causes, and providing practical techniques to resolve it, ensuring a smooth and efficient Python coding experience.

September 3, 2025 - If you forget to import a module, Python won’t recognize it. # Wrong print(math.sqrt(25)) # Correct import math print(math.sqrt(25)) I once ran into this while working with U.S. financial data and forgot to import pandas. Always check your imports. Sometimes, you may not be sure if a variable exists. In such cases, you can handle it gracefully with try/except. try: print(city) except NameError: print("The variable 'city' is not defined yet.")

June 27, 2022 - You'll see what a NameError is, some code examples to show how/why the error occurs, and how to fix them. In Python, the NameError occurs when you try to use a variable, function, or module that doesn't exist or wasn't used in a valid way.

December 8, 2024 - The Python NameError occurs when Python cannot recognise a name in your program. A name can be either related to a built-in function or to something you define in your program (e.g.

May 30, 2026 - This sequential execution model is intuitive but trips people up when code is reorganised — moving a line of computation above the variable assignments that it depends on immediately causes a NameError. If you move code around and start getting NameErrors, check whether all the variables it references are still defined before it. Python treats username, user_name, and usernme as completely separate names.