Couldn’t find a tree builder with the features you requested: html5lib.

html5lib是一个html解析库，使用BeautifulSoup进行解析html会用到。当然也可以使用python自带的库html.parser不过兼容性没有html5lib好。 html5lib不是自带，使用的时候需要安装一下。

安装 html5lib 解析库

pip3 install html5lib

如果使用的时候没有安装，会提示如下的的错误

!python3 a.py

Traceback (most recent call last):
  File "a.py", line 5, in <module>
    bsObj = BeautifulSoup(html.read(), "html5lib")
  File "/usr/local/python3/lib/python3.7/site-packages/bs4/__init__.py", line 196, in __init__
    % ",".join(features))
bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: html5lib. Do you need to install a parser library?

shell returned 1

了解更多： https://pypi.org/project/html5lib/

beautifulsoup4 安装

pip3 install beautifulsoup4

测试

from urllib.request import urlopen
from bs4 import BeautifulSoup

html = urlopen("https://www.liuhaolin.com");
bsObj = BeautifulSoup(html.read(), "html5lib")
# bsObj = BeautifulSoup(html.read(), "html.parser")

print(bsObj.title);