Selenium “Unable to find a matching set of capabilities” despite driver being in /usr/local/bin

Question

I was trying to open the firefox browser using selenium webdriver. I already have my geckodriver in /usr/local/bin as I'm working on project of web scraping and crawling.

• Geckodriver version-21.0
• Firefox version-64.0 (quantum)
• Selenium version- 3.141.0.

Also tried geckodriver of versions i.e 17.0,19.0,23.0; to find the combination.

What I have tried is in the following code.

from selenium import webdriver
from selenium.webdriver.support.select import Select
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions
from selenium.webdriver.common.keys import Keys
from bs4 import BeautifulSoup

driver=webdriver.Firefox()
driver.get("https://kissanime.ru/")
driver.maximize_window()

While executing the code it popped an error:

Traceback (most recent call last):
  File "downloader.py", line 9, in <module>
    driver=webdriver.Firefox()
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/firefox/webdriver.py", line 174, in __init__
keep_alive=True)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 157, in __init__
    self.start_session(capabilities, browser_profile)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 252, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.SessionNotCreatedException: Message: Unable to find a matching set of capabilities

Answer 1

This error message...

selenium.common.exceptions.SessionNotCreatedException: Message: Unable to find a matching set of capabilities

...implies that the GeckoDriver was unable to initiate/spawn a new WebBrowsing Session i.e. Firefox Browser session.

Your main issue may be the incompatibility between the version of the binaries you are using as follows:

Solution

• Upgrade Selenium to current levels Version 3.141.59.
• Upgrade GeckoDriver to GeckoDriver v0.23.0 level.
• Ensure GeckoDriver is present in the specified location.
• Ensure GeckoDriver is having executable permission for non-root users.
• Upgrade Firefox version to Firefox v64.0. levels.
• Clean your Project Workspace through your IDE and Rebuild your project with required dependencies only.
• (WindowsOS only) Use CCleaner tool to wipe off all the OS chores before and after the execution of your Test Suite.
• (LinuxOS only) Free Up and Release the Unused/Cached Memory in Ubuntu/Linux Mint before and after the execution of your Test Suite.
• If your base Web Client version is too old, then uninstall it through Revo Uninstaller and install a recent GA and released version of Web Client.
• Take a System Reboot.

• Pass the argument executable_path along with the absolute path of the GeckoDriver while initiating the WebDriver/WebBrowser session as follows:

  • Windows OS format:

    driver = webdriver.Firefox(executable_path=r'C:\path\to\geckodriver.exe')
    

  • Linux and MAC OS X format:

    driver = webdriver.Firefox(executable_path='/path/to/geckodriver')
    

• Execute your Test as a non-root user.

• Always invoke driver.quit() within tearDown(){} method to close & destroy the WebDriver and Web Client instances gracefully.