Fix Python NameError: Name 'True' Not Defined

Python is a powerful programming language. But beginners often face errors. One common error is NameError: Name 'True' is Not Defined.

This error occurs when Python cannot find the name True in the code. It usually happens due to typos or incorrect usage.

What Causes the NameError?

The NameError occurs when Python encounters an undefined name. For example, if you write true instead of True, Python will raise this error.

Python is case-sensitive. So, True and true are different. Always use the correct case for Python keywords.

Example of NameError: Name 'True' Not Defined

Here is an example that causes the error:

    # Incorrect code
    if true:
        print("This is true")
    

Running this code will result in the following error:

    NameError: name 'true' is not defined
    

The error occurs because true is not defined. Python expects True for boolean values.

How to Fix the NameError

To fix the error, ensure you use the correct keyword. Replace true with True.

    # Corrected code
    if True:
        print("This is true")
    

Now, the code will run without errors. The output will be:

    This is true
    

Always double-check your code for typos. This simple step can save you time debugging.

Common Scenarios Leading to NameError

Here are some common scenarios where this error might occur:

• Using lowercase true instead of True.
• Misspelling True as Ture or Tru.
• Using True in a scope where it is not defined.

For more details on handling such errors, check out our guide on Why Does NameError Occur in Python?.

Using Try-Except Blocks to Handle NameError

You can use try-except blocks to handle NameError gracefully. This is useful in larger programs.

    try:
        if true:
            print("This is true")
    except NameError:
        print("NameError: 'true' is not defined. Did you mean 'True'?")
    

This will catch the error and print a helpful message. Learn more about Handling NameError in Python Try-Except Blocks.

Conclusion

The NameError: Name 'True' is Not Defined is a common issue for beginners. It happens due to typos or incorrect usage of Python keywords.

Always use the correct case for Python keywords like True, False, and None. Double-check your code to avoid such errors.

For more tips on debugging Python errors, visit our guide on How to Fix NameError in Python.