title: selenium.common.exceptions.SessionNotCreatedException: Message: Unable to find a matching set of capabilities with Firefox 46 through Selenium
body: <p>I must have some versions here that don't match up since I can't get Selenium with Python to fire up a Firefox web browser. I'm using an older version of Firefox because other people in here have the same old version of Python and for them the old version of Firefox works best.</p>
  
  <p>Code:</p>
  
  <pre><code>from selenium import webdriver
  from selenium import common
  from selenium.webdriver import ActionChains
  from selenium.webdriver.common.by import By
  from selenium.webdriver.support.ui import WebDriverWait
  from selenium.webdriver.support import expected_conditions as EC
  from selenium.common.exceptions import TimeoutException
  from selenium.common.exceptions import NoSuchElementException
  from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
  driver=webdriver.Firefox(capabilities=DesiredCapabilities.FIREFOX)
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "scrapeCommunitySelenium.py", line 13, in &lt;module&gt;
      driver=webdriver.Firefox(capabilities=DesiredCapabilities.FIREFOX)
    File "/Library/Python/2.7/site-packages/selenium/webdriver/firefox/webdriver.py", line 158, in __init__
      keep_alive=True)
    File "/Library/Python/2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 154, in __init__
      self.start_session(desired_capabilities, browser_profile)
    File "/Library/Python/2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 243, in start_session
      response = self.execute(Command.NEW_SESSION, parameters)
    File "/Library/Python/2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 311, in execute
      self.error_handler.check_response(response)
    File "/Library/Python/2.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 237, in check_response
      raise exception_class(message, screen, stacktrace)
  selenium.common.exceptions.SessionNotCreatedException: Message: Unable to find a matching set of capabilities
  </code></pre>
  
  <p>Version info:</p>
  
  <ul>
  <li>Python 2.7.10 </li>
  <li>Selenium 3.8.0 </li>
  <li>Firefox 46.0 </li>
  <li>GeckoDriver 0.19.1 (It's in a folder which is in my PATH environment variable)</li>
  <li>MacOS 10.12.6</li>
  </ul>