How to catch HTTP 404 error in Python

Hi guys! In this tutorial, we will learn how to catch an HTTP 404 error in Python. There are many instances when we encounter an HTTP error with error code 404 on the internet. This error indicates that the requested page was not found. This tutorial will teach you how you can use Python to spot pages with such an error. Let’s see more on this with example programs.

Catch HTTP 404 error in Python

There are many methods for catching a 404 error. We will import the urllib or urllib3 library in this post for catching a 404 error. These library has required methods and attributes for our purpose. Let’s see the code and understand how it’s done.

Method 1

See the below example to find out a page with an HTTP 404 error.

import urllib3

http = urllib3.PoolManager()
error = http.request("GET", "https://www.google.com/404")
if (error.status == 404):
    print("HTTP 404 ERROR")

The output for the above code is:

HTTP 404 ERROR

In the above example, we have used the PoolManager of urllib3 to create an http object. A PoolManager instance is needed to make requests. Then we have used the request method to get an HTTPResponse object for the web page ‘https://www.google.com/404’. This HTTPResponse object contains status, data, and header. We check whether the status for this page is 404 if so we print that this is an HTTP error.

Method 2

In this method, we will import the Python urllib library. Have a look at the given code and try to understand.

import urllib.request, urllib.error

try:
    con = urllib.request.urlopen('http://www.google.com/404')

except urllib.error.HTTPError as err:
    print('HTTP', err.code, 'ERROR')

The output of the program:

HTTP 404 ERROR

As you can see, the urlopen() method opens the given URL for us. We have used try and except blocks to catch the HTTP error using urllib.error.HTTPError. If any error is raised while opening the URL, the control is given to except block and there we print the error code for HTTP error.

Thank you.

Also read: How to handle an attribute error in Python