Исходный код для урока (https://youtu.be/KPXPr-KS-qk)

weblancer.py

#!/usr/bin/env python3

import csv
import urllib.request

from bs4 import BeautifulSoup


BASE_URL = 'http://www.weblancer.net/projects/'


def get_html(url):
    response = urllib.request.urlopen(url)
    return response.read()


def get_page_count(html):
    soup = BeautifulSoup(html)
    paggination = soup.find('div', class_='pages_list text_box')
    return int(paggination.find_all('a')[-2].text)


def parse(html):
    soup = BeautifulSoup(html)
    table = soup.find('table', class_='items_list')
    rows = table.find_all('tr')[1:]

    projects = []
    for row in rows:

        cols = row.find_all('td')

        projects.append({
            'title': cols[0].a.text,
            'categories': [category.text for category in cols[0].find_all('noindex')],
            'price': cols[1].text.strip().split()[0],
            'application': cols[2].text.split()[0]
        })

    return projects

def save(projects, path):
    with open(path, 'w') as csvfile:
        writer = csv.writer(csvfile)

        writer.writerow(('Проект', 'Категории', 'Цена', 'Заявки'))

        writer.writerows(
            (project['title'], ', '.join(project['categories']), project['price'], project['application']) for project in projects
        )

def main():
    total_pages = get_page_count(get_html(BASE_URL))

    print('Всего найдено %d страниц...' % total_pages)

    projects = []

    for page in range(1, total_pages + 1):
        print('Парсинг %d%% (%d/%d)' % (page / total_pages * 100, page, total_pages))
        projects.extend(parse(get_html(BASE_URL + "page=%d" % page)))

    print('Сохранение...')
    save(projects, 'projects.csv')


if __name__ == '__main__':
    main()

Подскажите, пожалуйста, в чем причина ошибки
weblancer.py:18: UserWarning: No parser was explicitly specified, so I'm using the best available HTML parser for this system ("html.parser"). This usually isn't a problem, but if you run this code on another system, or in a different virtual environment, it may use a different parser and behave differently.

The code that caused this warning is on line 18 of the file weblancer.py. To get rid of this warning, pass the additional argument 'features="html.parser"' to the BeautifulSoup constructor.

soup = BeautifulSoup(html)
Traceback (most recent call last):
File "weblancer.py", line 68, in
main()
File "weblancer.py", line 53, in main
total_pages = get_page_count(get_html(BASE_URL))
File "weblancer.py", line 20, in get_page_count
return int(paggination.find_all('a')[-2].text)
AttributeError: 'NoneType' object has no attribute 'find_all'

@llirikkcoder, если еще актуально, то ошибка вываливается из-за того, что сайт перешел на другую структуру html-кода. Этот парсер пытается найти блоки с несуществующими классами и т.д.

Ниже мой вариант рабочего парсера:

#!/usr/bin/env python3

import csv
import requests

from bs4 import BeautifulSoup


BASE_URL = 'https://www.weblancer.net/jobs/'


def get_html(url):
    response = requests.get(url)
    if response.status_code == 200:
        return response.content
    else:
        print ("Error")
        quit()


def get_page_count(html):
    soup = BeautifulSoup(html, features="lxml")
    paggination = soup.find('div', class_='pagination_box')
    return int(paggination.find_all('a')[-1]['href'].split("=")[1])


def parse(html):
    soup = BeautifulSoup(html, features="lxml")
    table = soup.find('div', class_='page_content').find('div', class_='cols_table')

    rows = table.find_all('div', class_='row')

    projects = []
    nmbr = 1
    for row in rows:

        # Знак валюты в конец строки
        price = row.find('div', class_='float-right float-sm-none title amount indent-xs-b0').text
        if price != '':
            price=price[1:]+price[0]

        projects.append({
            'title': row.find('h2').text,
            'short_description': row.find('p').text,
            'categories': [category.text for category in row.find('div', class_='col-sm-8 text-muted dot_divided').find_all('a')],
            'price': price,
            'application': row.find('div', class_='float-left float-sm-none text_field').text.strip()
        })

    return projects

def save(projects, path):
    with open(path, 'w') as csvfile:
        writer = csv.writer(csvfile)

        writer.writerow(('Проект', 'Краткое описание', 'Категории', 'Цена', 'Заявки'))

        writer.writerows(
            (project['title'], project['short_description'], project['categories'], project['price'], project['application']) for project in projects
        )

def main():

    total_pages = get_page_count(get_html(BASE_URL))

    print('Всего найдено %d страниц...' % total_pages)

    projects = []

    for page in range(1, total_pages + 1):
        print('Парсинг %d%% (%d/%d)' % (page / total_pages * 100, page, total_pages))
        projects.extend(parse(get_html(BASE_URL + "?page=%d" % page)))

    print('Сохранение...')
    save(projects, 'projects.csv')
    print('Готово!')


if __name__ == '__main__':
    main()