TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'

This error occurs when you are trying to perform an operation or comparison on two variables, but one or both of them have a value of None. None is a special keyword in Python that represents the absence of a value.

For example, if you try to add two variables together, but one of them is None:

a = None
b = 5
c = a + b

You will get the error message:

TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'

To fix this error, you need to make sure that all variables have a valid value before performing any operations or comparisons. You can use conditional statements to check if a variable is None before using it in your code.