How do I catch a specific HTTP error in Python?

I have

import urllib2
try:
   urllib2.urlopen("some url")
except urllib2.HTTPError:
   <whatever>

but what I end up is catching any kind of HTTP error. I want to catch only if the specified webpage doesn’t exist (404?).

Answer

Python 3

from urllib.error import HTTPError

Python 2

from urllib2 import HTTPError

Just catch HTTPError, handle it, and if it’s not Error 404, simply use raise to re-raise the exception.

See the Python tutorial.

Here is a complete example for Python 2:

import urllib2
from urllib2 import HTTPError
try:
   urllib2.urlopen("some url")
except HTTPError as err:
   if err.code == 404:
       <whatever>
   else:
       raise