WebDriverException: Message: The browser appears to have exited before we could connect error with GeckoDriver Selenium and Python

Question

There are about 100 posts about the same issue but none of them seem to work for me, hence asking again. I'm trying to launch a Firefox browser using Python and Selenium and I get the following error:

WebDriverException: Message: The browser appears to have exited before we could connect. If you specified a log_file in the FirefoxBinary constructor, check it for details.

I tried each and every answer on the web but nothing seems to work.

This is my code:

from selenium import webdriver
from selenium.webdriver.firefox.options import Options
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

caps = DesiredCapabilities.FIREFOX
caps["marionette"] = False

binary = FirefoxBinary('d:\\Desktop\\IEDriver\\geckodriver.exe')

options = Options()
options.set_headless(headless=True)
driver = webdriver.Firefox(firefox_binary=binary, firefox_options=options, executable_path=r'd:\\Desktop\\IEDriver\\geckodriver.exe')
driver.get("http://google.com/")
print ("Headless Firefox Initialized")
driver.quit()

If I set caps["marionette"] = True then the error I get is

SessionNotCreatedException: Message: Unable to find a matching set of capabilities

Versions of software I'm running:

Firefox: 62.0 (64 bit)

Selenium: 3.14.0

Gecko: 0.21.0

Python: 3

OS: Windows 8.1 64 bit

Any help would be highly appreciated.

EDIT: I've uninstalled and re-installed Firefox but didn't work. Also tried installing Firefox 61.0.2, still no luck.

Answer 1

This error message...

WebDriverException: Message: The browser appears to have exited before we could connect. 
If you specified a log_file in the FirefoxBinary constructor, check it for details.

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

You need to take care of a couple of things as follows:

• To set the FirefoxBinary you need to use the FirefoxOptions() and instead of passing the absolute path of geckodriver binary, you have to pass the absolute path of the desired firefox binary.
• As you are using GeckoDriver v0.21.0 you have to mandatorily use marionette so either keep it unchanged (by default true) or set marionette to true.

• Your own code with incorporating the minor changes will be:

  from selenium import webdriver
  from selenium.webdriver.firefox.options import Options
  from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
  
  binary = r'C:\Program Files\Mozilla Firefox\firefox.exe'
  options = Options()
  options.set_headless(headless=True)
  options.binary = binary
  cap = DesiredCapabilities().FIREFOX
  cap["marionette"] = True #optional
  driver = webdriver.Firefox(firefox_options=options, capabilities=cap, executable_path="C:\\Utility\\BrowserDrivers\\geckodriver.exe")
  driver.get("http://google.com/")
  print ("Headless Firefox Initialized")
  driver.quit()
  

• Console Output:

  Headless Firefox Initialized
  

• Here you can find a detailed discussion on Unable to find a matching set of capabilities with selenium 3.4.3, firefox 54.0 and gecko driver 0.17