Selenium and Geckodriver issue with creating a webdriver in Python

Question

I have a piece of code in a python crawler that used to work. I installed it on a new system, and am trying to get the right dependencies now. When using geckodriver 0.13.0 and executing the following code:

        def login(self):
            print self.colors.OKBLUE + "Logging into my site as User: " + self.config.email + self.colors.ENDC
            username = self.driver.find_element_by_css_selector('.my_user_field')
            for c in self.config.email:
                    print "Sending key: " + c
                    username.send_keys(c + "")

I get the following error:

Sending key: b
Traceback (most recent call last):
  File "main.py", line 20, in <module>
    crawler.start()
  File "/home/tyrick/dev/pycrawlers/sc/src/main/python/new.py", line 39, in start
    self.login()
  File "/home/tyrick/dev/pycrawlers/sc/src/main/python/new.py", line 147, in login
username.send_keys(c)
   File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webelement.py", line 349, in send_keys
    'value': keys_to_typing(value)})
   File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webelement.py", line 493, in _execute
    return self._parent.execute(command, params)
   File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 256, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Expected [object Undefined] undefined to be a string

I read in a few places that geckodriver has a bug with this, and I should use 0.16.0. So I've tried that as well as 0.17.0, but am now getting the following error:

Traceback (most recent call last):
  File "main.py", line 18, in <module>
    crawler = New()
  File "/home/tyrick/dev/pycrawlers/sc/src/main/python/new.py", line 28, in __init__
    self.driver = webdriver.Firefox()
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.py", line 152, in __init__
keep_alive=True)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 98, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 188, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 256, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: elementScrollBehavior was not a the name of a known capability or a valid extension capability

It's as if I now can't even initialize the driver. I am using Selenium 3.4.3, which from what I read is fine.

If anyone can guide me towards a solution, I’d appreciate it much! Thanks

Answer 1

You are right, you have two different issues.

Issue with geckodriver 0.13.0:

This is most likely because your c is undefined.

You have to verify/assert that self.config.email actually returns a valid string (email). So do a check that c contains your expected email before issuing the .send_keys() command.

Another enhancement worth noting here is your lack of safety when it comes to finding the username field. You should use an explicit wait !

# Library imports
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

# (...)

def login(self):
    print self.colors.OKBLUE + "Logging into my site as User: " + 
    self.config.email + self.colors.ENDC

    # Polls the DOM for 3 seconds trying to find '.my_user_field'
    username = WebDriverWait(self.driver, 3).until(EC.presence_of_element_located((By.CSS_SELECTOR, '.my_user_field')))

    for c in self.config.email:

        # Validate 'c' is of type string
        if (str(type(c)).find('str') != -1):  
            print "Sending key: " + c
            username.send_keys(c + "")
        else:
            print "'c' is not what it used to be!"

Lastly, add the full snippet because it looks like you're cycling through a list of emails and sending them in the previously found username field.

Issue with geckodriver 0.16.0:

This is failing because you have an issue with your driver instantiation: self.driver = webdriver.Firefox().

Please update the question with the complete snippet of your driver declaration (including capabilities & profiles, if any). Else, it's really hard to figure out the cause of the error.