TypeError: super().__init__() Missing Arguments

Why This Happens

When subclassing, you must call the parent __init__ with required arguments. If the parent expects parameters but you call super().__init__() without them, Python raises TypeError.

The Problem

class AppError(Exception):
    def __init__(self, code):
        super().__init__()
        self.code = code

The Fix

class AppError(Exception):
    def __init__(self, message, code):
        super().__init__(message)
        self.code = code

raise AppError('Something failed', 500)

Step-by-Step Fix

1. 1

   Check parent __init__

   Look at what arguments the parent class expects.

2. 2

   Pass required arguments

   Forward all necessary arguments to super().__init__().

3. 3

   Document the interface

   Make it clear what arguments your subclass constructor expects.