'NoneType' Object is Not Subscriptable Error in Python: Causes and Solutions

The error message 'NoneType' object is not subscriptable' typically occurs when you attempt to access an index or attribute of an object that is of 'None' type. In Python, 'None' is a special object representing the absence of a value.

Here's an example illustrating the error:

my_list = None
print(my_list[0])  # Raises 'NoneType' object is not subscriptable error

In this instance, my_list is assigned the value 'None', and trying to access the index 0 of 'None' raises the error because 'None' is not a subscriptable object.

To resolve this error, you must ensure that the object you are attempting to access is not 'None'. This can be achieved by checking if an object is 'None' before trying to access its index or attribute.

Here's an updated example:

my_list = [1, 2, 3]
if my_list is not None:
    print(my_list[0])  # Prints 1
else:
    print('my_list is None')

In this case, the code checks if my_list is not 'None' before accessing its index 0. If my_list is 'None', it prints a message indicating that my_list is 'None'. Otherwise, it prints the value at index 0.