Python urllib2 URLError exception?

Question

I installed Python 2.6.2 earlier on a Windows XP machine and run the following code:

import urllib2
import urllib

page = urllib2.Request('http://www.python.org/fish.html')
urllib2.urlopen( page )

I get the following error.

Traceback (most recent call last):<br>
  File "C:\Python26\test3.py", line 6, in <module><br>
    urllib2.urlopen( page )<br>
  File "C:\Python26\lib\urllib2.py", line 124, in urlopen<br>
    return _opener.open(url, data, timeout)<br>
  File "C:\Python26\lib\urllib2.py", line 383, in open<br>
    response = self._open(req, data)<br>
  File "C:\Python26\lib\urllib2.py", line 401, in _open<br>
    '_open', req)<br>
  File "C:\Python26\lib\urllib2.py", line 361, in _call_chain<br>
    result = func(*args)<br>
  File "C:\Python26\lib\urllib2.py", line 1130, in http_open<br>
    return self.do_open(httplib.HTTPConnection, req)<br>
  File "C:\Python26\lib\urllib2.py", line 1105, in do_open<br>
    raise URLError(err)<br>
URLError: <urlopen error [Errno 11001] getaddrinfo failed><br><br><br>

Answer 1

Have a look in the urllib2 source, at the line specified by the traceback:

File "C:\Python26\lib\urllib2.py", line 1105, in do_open
raise URLError(err)

There you'll see the following fragment:

    try:
        h.request(req.get_method(), req.get_selector(), req.data, headers)
        r = h.getresponse()
    except socket.error, err: # XXX what error?
        raise URLError(err)

So, it looks like the source is a socket error, not an HTTP protocol related error. Possible reasons: you are not on line, you are behind a restrictive firewall, your DNS is down,...

All this aside from the fact, as mcandre pointed out, that your code is wrong.

Answer 2

import urllib2
response = urllib2.urlopen('http://www.python.org/fish.html')
html = response.read()

You're doing it wrong.

Answer 3

Windows Vista, python 2.6.2

It's a 404 page, right?

>>> import urllib2
>>> import urllib
>>>
>>> page = urllib2.Request('http://www.python.org/fish.html')
>>> urllib2.urlopen( page )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python26\lib\urllib2.py", line 124, in urlopen
    return _opener.open(url, data, timeout)
  File "C:\Python26\lib\urllib2.py", line 389, in open
    response = meth(req, response)
  File "C:\Python26\lib\urllib2.py", line 502, in http_response
    'http', request, response, code, msg, hdrs)
  File "C:\Python26\lib\urllib2.py", line 427, in error
    return self._call_chain(*args)
  File "C:\Python26\lib\urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "C:\Python26\lib\urllib2.py", line 510, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
urllib2.HTTPError: HTTP Error 404: Not Found
>>>

Answer 4

DJ

First, I see no reason to import urllib; I've only ever seen urllib2 used to replace urllib entirely and I know of no functionality that's useful from urllib and yet is missing from urllib2.

Next, I notice that http://www.python.org/fish.html gives a 404 error to me. (That doesn't explain the backtrace/exception you're seeing. I get urllib2.HTTPError: HTTP Error 404: Not Found

Normally if you just want to do a default fetch of a web pages (without adding special HTTP headers, doing doing any sort of POST, etc) then the following suffices:

req = urllib2.urlopen('http://www.python.org/')
html = req.read()
# and req.close() if you want to be pedantic

Answer 5

Name resolution error.

getaddrinfo is used to resolve the hostname (python.org)in your request. If it fails, it means that the name could not be resolved because:

1. It does not exist, or the records are outdated (unlikely; python.org is a well-established domain name)
2. Your DNS server is down (unlikely; if you can browse other sites, you should be able to fetch that page through Python)
3. A firewall is blocking Python or your script from accessing the Internet (most likely; Windows Firewall sometimes does not ask you if you want to allow an application)
4. You live on an ancient voodoo cemetery. (unlikely; if that is the case, you should move out)