Python TypeError: 'NoneType' object is not subscriptable - Explained and Solved

This error occurs when you try to access an index or a key of a variable that is of type 'None'. 'None' is a special value in Python that represents the absence of a value.

For example, if you have a function that returns 'None', and you try to access an index of that function's return value:

def my_function():
    return None

result = my_function()[0]

This will raise a TypeError, because you are trying to access the first element of 'None', which is not possible.

To fix this error, you need to check if the variable is 'None' before trying to access its indices or keys:

my_var = None

if my_var is not None:
    result = my_var[0]
else:
    result = None

In this example, if 'my_var' is 'None', the if statement will not execute, and 'result' will be set to 'None'. If 'my_var' is not 'None', the if statement will execute, and 'result' will be set to the first element of 'my_var'.