爬CSDN博客文章的代码，为什么登录失败了

[乐百川]

import requests
from bs4 import BeautifulSoup
import re


class CsdnHelper:
    csdn_login_url = 'https://passport.csdn.net/account/login?ref=toolbar'
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36',
        'Content-Type': 'application/x-www-form-urlencoded',
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
        'DNT': '1',
        'Referer': 'https://passport.csdn.net/account/login?ref=toolbar',
        'Accept-Encoding': 'gzip, deflate, br',
        'Accept-Language': 'zh-CN,zh;q=0.8,en;q=0.6,ja;q=0.4',
    }

    def __init__(self):
        self._session = requests.session()
        self._session.headers = CsdnHelper.headers

    def login(self, username, password):
        form_data = self._prepare_login_form_data(username, password)
        response = self._session.post(CsdnHelper.csdn_login_url, data=form_data)
        print(response.text)
        if 'UserNick' in response.cookies:
            print(response.cookies['UserNick'])
        else:
            raise Exception('登录失败')

    def _prepare_login_form_data(self, username, password):
        response = self._session.get(CsdnHelper.csdn_login_url)
        login_page = BeautifulSoup(response.text, 'lxml')
        login_form = login_page.find('form', id='fm1')

        lt = login_form.find('input', attrs={'name': 'lt'})['value']
        execution = login_form.find('input', attrs={'name': 'lt'})['value']
        eventId = login_form.find('input', attrs={'name': 'lt'})['value']
        form = {
            'username': username,
            'password': password,
            'lt': lt,
            'execution': execution,
            '_eventId': eventId
        }

        return form

    def _get_blog_count(self):

        blog_base_url = 'http://write.blog.csdn.net/postlist/'
        response = self._session.get(blog_base_url)
        blog_page = BeautifulSoup(response.text, 'lxml')
        span = blog_page.find('div', class_='page_nav').span
        pattern = re.compile(r'(\d+)条 共(\d*)页')
        result = pattern.match(span.string)
        blog_count = int(result.group(1))
        page_count = int(result.group(2))
        return (blog_count, page_count)

    def print_blogs(self):
        blog_count, page_count = self._get_blog_count()
        for index in range(1, page_count + 1):
            url = f'http://write.blog.csdn.net/postlist/0/0/enabled/{index}'
            response = self._session.get(url)
            page = BeautifulSoup(response.text, 'lxml')
            links = page.find_all('a', href=re.compile(r'http://blog.csdn.net/u011054333/article/details/(\d+)'))
            print(f'----------第{index}页----------')
            for link in links:
                blog_name = link.string
                blog_url = link['href']
                print(f'文章名称:{blog_name} 文章链接:{blog_url}')


if __name__ == '__main__':
    csdn_helper = CsdnHelper()
    username = XXX
    password = XXX
    csdn_helper.login(username, password)

我感觉几个部分写的都挺对的，结果登录URL返回的是一个错误页面。但是我浏览器登录好好的，请问我这代码哪里不对？