`TypeError`

TypeError is a built-in exception that occurs when an operation is applied to an object of inappropriate type. For example, trying to add a string to an integer will raise a TypeError because these types implement addition in different and incompatible ways.

You should use this exception to catch and handle errors that occur due to invalid types in your code.

`TypeError` Occurs When

Attempting to perform operations on objects of incompatible types, such as adding a string and an integer
Using unsupported operations on a type, like calling a method that doesn’t exist for a particular type
Calling an object that isn’t a callable

`TypeError` Can Be Used When

Notifying users of your code about incorrect usage of your custom functions and methods
Handling multiple situations in your code following EAFP

`TypeError` Examples

An example of when the exception appears:

Python
      
        
      
    
>>> len(42)
Traceback (most recent call last):
    ...
TypeError: object of type 'int' has no len()

>>> "Hello"()
Traceback (most recent call last):
    ...
TypeError: 'str' object is not callable

An example of how to handle the exception:

Python
      
        
      
    
>>> def safe_add(a, b):
...     try:
...         return a + b
...     except TypeError:
...         print(f"{type(a)} and {type(b)} are incompatible for addition.")
...         return None
...

>>> safe_add(5, 10)
15
>>> safe_add(5, "10")
<class 'int'> and <class 'str'> are incompatible for addition.

An example of when you may want to raise the exception:

Python
      
        
      
    
>>> def run_callback(callback, *args, **kwargs):
...     if not callable(callback):
...         raise TypeError("callback must be callable")
...     return callback(*args, **kwargs)
...

>>> run_callback(42)
Traceback (most recent call last):
    ...
TypeError: callback must be callable

Tutorial

Python's Built-in Exceptions: A Walkthrough With Examples

In this tutorial, you'll get to know some of the most commonly used built-in exceptions in Python. You'll learn when these exceptions can appear in your code and how to handle them. Finally, you'll learn how to raise some of these exceptions in your code.

intermediate python

For additional information on related topics, take a look at the following resources: