How to Fix TypeError in Python: NoneType Object Is Not Iterable

The Python TypeError: NoneType Object Is Not Iterable is an exception that occurs when trying to iterate over a None value. Since in Python, only objects with a value can be iterated over, iterating over a None object raises the TypeError: NoneType Object Is Not Iterable exception.

What Causes TypeError: NoneType Object Is Not Iterable

For an object to be iterable in Python, it must contain a value. Therefore, trying to iterate over a None value raises the Python TypeError: NoneType Object Is Not Iterable exception. Some of the most common sources of None values are:

Calling a function that does not return anything.
Calling a function that sets the value of the data to None.
Setting a variable to None explicitly.

Python TypeError: NoneType Object Is Not Iterable Example

Here’s an example of a Python TypeError: NoneType Object Is Not Iterable thrown when trying iterate over a None value:

mylist = None

for x in mylist:
    print(x)

In the above example, mylist is attempted to be added to be iterated over. Since the value of mylist is None, iterating over it raises a TypeError: NoneType Object Is Not Iterable:

Traceback (most recent call last):
  File "test.py", line 3, in <module>
    for x in mylist:
TypeError: 'NoneType' object is not iterable

How to Fix TypeError in Python: NoneType Object Is Not Iterable

The Python TypeError: NoneType Object Is Not Iterable error can be avoided by checking if a value is None or not before iterating over it. This can help ensure that only objects that have a value are iterated over, which avoids the error.

Using the above approach, a check can be added to the earlier example:

mylist = None

if mylist is not None:
    for x in mylist:
        print(x)

Here, a check is performed to ensure that mylist is not None before it is iterated over, which helps avoid the error.

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