Typeerror: nonetype object does not support item assignment

When working with Python projects, we may come across an error that reads “Typeerror: nonetype object does not support item assignment”.

At first glance, this error message can seem cryptic and frustrating. However, it’s actually a helpful clue that points toward the root of the problem.

In this guide, we’ll explore the causes of this error as well as provide practical examples of how to resolve it.

By the end of this guide, we’ll have a better understanding of how to prevent and fix this error in Python.

What is Typeerror: nonetype object does not support item assignment?

The Python error TypeError: ‘NoneType’ object does not support item assignment occurs means that we are trying to assign a value to an object that has a value of None (or null in other programming languages).

Moreover, None is a special value that represents the absence of a value.

Thus it is often used as a default value for function arguments or to indicate that a variable has not been initialized.

Take a look at the next section on how this error occurs…

How to reproduce Typeerror: nonetype object does not support item assignment

Here’s an example code snippet that could produce this error:

x = None
x[0] = 1

In this code, we have a variable x that has not been assigned a value. Its value will be None by default.

Therefore if we try to assign a value to x[0], you will get a TypeError because you cannot assign a value to an index of None.

Traceback (most recent call last):
  File "C:\Users\Windows\PycharmProjects\pythonProject1\main.py", line 2, in <module>
    x[0] = 1
TypeError: 'NoneType' object does not support item assignment

Now let’s find the possible factors why and when we can get this error. Hence you might consider in finding solutions.

When do we get this error?

These are the common possible causes when we got the TypeError: ‘NoneType’ object does not support item assignment.

• Trying to assign a value to a variable that has not been initialized or is set to None.
• Using the wrong data type in an operation that requires a mutable object, such as a list or dictionary.
• Calling a function that returns None and trying to perform an item assignment on the result.
• Accessing an object that does not exist, which results in None.
• Overwriting a variable with a function that returns None, causing the variable to become None.
• Using the wrong variable name or referencing the wrong object in a function call.

This time let’s figure out what are the solutions to this error…

How to fix nonetype object does not support item assignment

Here are the possible solutions you can try in fixing the error nonetype object does not support item assignment.

Solution 1: Verify why the variable is assigned to the value None

The first way to fix the error is to ensure why the variable is assigned to None.

Meanwhile, if we assigned a mutable collection of objects (list, set, array, etc.) in a variable it will definitely fix the error.

For example:

my_var = [10,20,30]
my_var[0] = 10
print (my_var)

📌Output:

[10, 20, 30]

Solution 2: Skip assigning the value using the index if variable is None

In this solution, we should avoid assigning the value using the index, when the variable is assigned to None.

In short, accessing value with an index is pointless.

We should do this way instead:

my_var = None
if my_var is not None:
	my_var[0] = 5
print (my_var)

📌Output:

None

Solution 3: Create a list with a value assigned to None

Create a list with values assigned to when a variable is assigned to None needs to store values in the variable.

Moreover, the index should be available in the list. Wherein the list assigned to the value None is changeable by adding values to the index.

For example:

my_var = None
if my_var is None :
	my_var = [None] * 10
my_var[0] = 5
print (my_var)

📌Output:

[5, None, None, None, None, None, None, None, None, None]

Anyway, we also have a solution for Typeerror series objects are mutable thus they cannot be hashed errors, you might encounter.

Conclusion

To conclude, Typeerror: nonetype object does not support item assignment occurs when we are trying to assign a value to an object which has a value of None.

To fix this error, we need to make sure that the variable we are trying to access has a valid value before trying to assign an item to it.

I think that’s all for this guide. We hope you have learned and we helped you fix your error.

Thank you for reading! 😊

Glay Eliver

Programmer & Technical Writer at PIES IT Solution

Glay Eliver is a programmer and writer at PIES IT Solution, author of over 600 tutorials at itsourcecode.com. Specializes in JavaScript tutorials, Microsoft Office how-tos (Excel, Word, PowerPoint), and Python error debugging covering ImportError, TypeError, AttributeError, ModuleNotFoundError, and JavaScript ReferenceError. Authored several of the site’s highest-traffic Excel and MS Office reference articles.

Expertise: JavaScript · MS Excel · MS Word · MS PowerPoint · Python · Python ImportError · Python TypeError · Python AttributeError · ModuleNotFoundError · JavaScript ReferenceError · Pygame  · View all posts by Glay Eliver →