TypeError: greet() missing 1 required positional argument: 'name'

What it means

You called a function with fewer values than it needs. The message names the function and the parameters that got no value. Every parameter without a default value must receive one in the call.

1. Calling a function without its argument

This raises the error

Traceback (most recent call last):
  File "<exec>", line 4, in <module>
TypeError: greet() missing 1 required positional argument: 'name'

The fix

Hello, Ada!

The call now passes a value for name. If the argument should be optional, give it a default instead: def greet(name="friend"):.

Try fixing it yourself in the editor

2. Creating an object without the values `__init__` needs

This raises the error

Traceback (most recent call last):
  File "<exec>", line 5, in <module>
TypeError: Dog.__init__() missing 1 required positional argument: 'name'

The fix

Rex

Dog() runs __init__, which needs a name, so the message says Dog.__init__() missing 1 required positional argument: 'name'. Python fills in self for you, but every other parameter needs a value.

Try fixing it yourself in the editor

3. Calling a method on the class instead of an object

This raises the error

Traceback (most recent call last):
  File "<exec>", line 5, in <module>
TypeError: Dog.bark() missing 1 required positional argument: 'self'

The fix

Woof!

Python passes the object as self only when you call the method on an object. Dog.bark() has no object, so the message says missing 1 required positional argument: 'self'.

Try fixing it yourself in the editor

Related errors

• TypeError: add() takes 2 positional arguments but 3 were given
• NameError: name 'username' is not defined
• AttributeError: 'NoneType' object has no attribute