HTTP error 403 in Python 3 Web Scraping

This is probably because of mod_security or some similar server security feature which blocks known spider/bot user agents (urllib uses something like python urllib/3.3.0, it's easily detected). Try setting a known browser user agent with:

from urllib.request import Request, urlopen

req = Request('http://www.cmegroup.com/trading/products/#sortField=oi&sortAsc=false&venues=3&page=1&cleared=1&group=1', headers={'User-Agent': 'Mozilla/5.0'})
webpage = urlopen(req).read()

This works for me.

By the way, in your code you are missing the () after .read in the urlopen line, but I think that it's a typo.

TIP: since this is exercise, choose a different, non restrictive site. Maybe they are blocking urllib for some reason...

Definitely it's blocking because of your use of urllib based on the user agent. This same thing is happening to me with OfferUp. You can create a new class called AppURLopener which overrides the user-agent with Mozilla.

import urllib.request

class AppURLopener(urllib.request.FancyURLopener):
    version = "Mozilla/5.0"

opener = AppURLopener()
response = opener.open('http://httpbin.org/user-agent')

Source

"This is probably because of mod_security or some similar server security feature which blocks known

spider/bot

user agents (urllib uses something like python urllib/3.3.0, it's easily detected)" - as already mentioned by Stefano Sanfilippo

from urllib.request import Request, urlopen
url="https://stackoverflow.com/search?q=html+error+403"
req = Request(url, headers={'User-Agent': 'Mozilla/5.0'})

web_byte = urlopen(req).read()

webpage = web_byte.decode('utf-8')

The web_byte is a byte object returned by the server and the content type present in webpage is mostly utf-8. Therefore you need to decode web_byte using decode method.

This solves complete problem while I was having trying to scrap from a website using PyCharm

P.S -> I use python 3.4