bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml.

[maretodoric]

When trying to run the script, an error message appeared after trying to login to facebook. DEBUG log bellow:

[2020-05-21 16:41:41,728] fb2cal INFO (<module>) Starting fb2cal v1.0.4 (Production) [https://git.io/fjMwr]
[2020-05-21 16:41:41,730] fb2cal INFO (<module>) This project is released under the GPLv3 license.
[2020-05-21 16:41:41,730] fb2cal INFO (main) Attemping to parse config file config.ini...
[2020-05-21 16:41:41,733] fb2cal INFO (main) Config successfully loaded.
[2020-05-21 16:41:41,734] fb2cal INFO (main) Logging level set to: DEBUG
[2020-05-21 16:41:41,736] fb2cal INFO (main) Attemping to authenticate with Facebook...
[2020-05-21 16:41:41,744] urllib3.connectionpool DEBUG (_new_conn) Starting new HTTP connection (1): www.facebook.com:80
[2020-05-21 16:41:41,838] urllib3.connectionpool DEBUG (_make_request) http://www.facebook.com:80 "GET /login.php HTTP/1.1" 302 0
[2020-05-21 16:41:41,844] urllib3.connectionpool DEBUG (_new_conn) Starting new HTTPS connection (1): www.facebook.com:443
[2020-05-21 16:41:42,059] urllib3.connectionpool DEBUG (_make_request) https://www.facebook.com:443 "GET /login.php HTTP/1.1" 200 None
Traceback (most recent call last):
  File "src/fb2cal.py", line 743, in <module>
    main()
  File "src/fb2cal.py", line 113, in main
    facebook_authenticate(browser, config['AUTH']['FB_EMAIL'], config['AUTH']['FB_PASS'])
  File "src/fb2cal.py", line 214, in facebook_authenticate
    login_page = browser.get(FACEBOOK_LOGIN_URL)
  File "/usr/local/lib/python3.7/dist-packages/mechanicalsoup/browser.py", line 127, in get
    Browser.add_soup(response, self.soup_config)
  File "/usr/local/lib/python3.7/dist-packages/mechanicalsoup/browser.py", line 70, in add_soup
    response.soup = bs4.BeautifulSoup(response.content, **soup_config)
  File "/usr/local/lib/python3.7/dist-packages/bs4/__init__.py", line 245, in __init__
    % ",".join(features))
bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?

I was running this on Raspberry Pi 3 (Raspbian 10), Python 3.7.3.
I have installer prerequisites prior to running the app as described and lxml is installed, see the output bellow:

root@raspberrypi:~/fb2cal# python3 --version
Python 3.7.3
root@raspberrypi:~/fb2cal# python3 -m pip install lxml
Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
Requirement already satisfied: lxml in /usr/local/lib/python3.7/dist-packages (4.5.1)

But the error still persisted. I managed to get this resolved by changing lxml to html.parser on src/fb2cal.py line #624 from:
day_name = BeautifulSoup(birthday_date_str, 'lxml').get_text().lower()
to
day_name = BeautifulSoup(birthday_date_str, 'html.parser').get_text().lower()

and file /usr/local/lib/python3.7/dist-packages/mechanicalsoup/browser.py line #35 from
def __init__(self, session=None, soup_config={'features': 'lxml'},
to
def __init__(self, session=None, soup_config={'features': 'html.parser'},

After that, worked like a charm, successfully imported calendar to google.
It might need to be checked why it ignored lxml but worked fine with html.parser.

[mobeigi]

So I think the Pi just wasn't able to support lxml (maybe due to dependancies). A good solution here would be to prefer lxml and then fallback to html.parser if its unavailable.

[joseparreiras]

Seems like this error is back. I tried to run the latest version on my MacOS and I still get this.

[mobeigi]

@joseparreiras Hmm honestly lxml has been a problem for a few people due to the external dependancy.

Since speed isn't a real problem with this tool, I might just change the parser to html.parser to fix the issue on a fair few platforms.

[joseparreiras]

Can I do it quickly myself?