title: Python: Selenium Firefox Webdriver failing with error: 'Can't load the profile...WARN addons.xpi..."
body: <p>I am trying to run the following Python code to create a Firefox Webdriver window via Selenium:</p>
  
  <pre><code>from selenium import webdriver
  driver = webdriver.Firefox()
  driver.get("http://www.google.com")
  </code></pre>
  
  <p>While this code worked fine a few weeks ago, it now produces the following foreboding message:</p>
  
  <pre><code> Traceback (most recent call last):
    File "test.py", line 2, in &lt;module&gt;
      driver = webdriver.Firefox()
    File "c:\python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 60, in __init__
      self.binary, timeout),
    File "c:\python27\lib\site-packages\selenium\webdriver\firefox\extension_connection.py", line 47, in __init__
      self.binary.launch_browser(self.profile)
    File "c:\python27\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py", line 61, in launch_browser
      self._wait_until_connectable()
    File "c:\python27\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py", line 105, in _wait_until_connectable
      self.profile.path, self._get_firefox_output()))
  selenium.common.exceptions.WebDriverException: Message: 'Can\'t load the profile. Profile Dir: c:\\users\\douglas\\appdata\\local\\temp\\tmpuf4ipq Firefox output: *** LOG addons.xpi: startup\r\n*** WARN addons.xpi: Ignoring missing add-on in C:\\Program Files\\CheckPoint\\ZAForceField\\WOW64\\TrustChecker\r\n*** WARN addons.xpi: Ignoring missing add-on in C:\\ProgramData\\Norton\\{78CA3BF0-9C3B-40e1-B46D-38C877EF059A}\\NSM_2.9.5.20\\coFFFw\r\n*** LOG addons.xpi: Skipping unavailable install location app-system-local\r\n*** LOG addons.xpi: Skipping unavailable install location app-system-share\r\n*** LOG addons.xpi: checkForChanges\r\n*** LOG addons.xpi: No changes found\r\n*** Blocklist::_loadBlocklistFromFile: blocklist is disabled\r\n************************************************************\r\n* Call to xpconnect wrapped JSObject produced this error:  *\r\n[Exception... "\'[JavaScript Error: "this._defaultEngine is null" {file: "resource://gre/components/nsSearchService.js" line: 3527}]\' when calling method: [nsIBrowserSearchService::currentEngine]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: chrome://browser/content/search/search.xml :: get_currentEngine :: line 130"  data: yes]\r\n************************************************************\r\n************************************************************\r\n* Call to xpconnect wrapped JSObject produced this error:  *\r\n[Exception... "\'[JavaScript Error: "this._defaultEngine is null" {file: "resource://gre/components/nsSearchService.js" line: 3527}]\' when calling method: [nsIBrowserSearchService::currentEngine]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: chrome://browser/content/search/search.xml :: get_currentEngine :: line 130"  data: yes]\r\n************************************************************\r\n************************************************************\r\n* Call to xpconnect wrapped JSObject produced this error:  *\r\n[Exception... "\'[JavaScript Error: "this._defaultEngine is null" {file: "resource://gre/components/nsSearchService.js" line: 3527}]\' when calling method: [nsIBrowserSearchService::currentEngine]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: resource://app/components/nsBrowserGlue.js :: &lt;TOP_LEVEL&gt; :: line 354"  data: yes]\r\n************************************************************\r\n************************************************************\r\n* Call to xpconnect wrapped JSObject produced this error:  *\r\n[Exception... "\'[JavaScript Error: "this._defaultEngine is null" {file: "resource://gre/components/nsSearchService.js" line: 3527}]\' when calling method: [nsIBrowserSearchService::currentEngine]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: resource://app/components/nsBrowserGlue.js :: &lt;TOP_LEVEL&gt; :: line 354"  data: yes]\r\n************************************************************\r\n'
  </code></pre>
  
  <p>Does anyone know what this means, or what I can do to remedy the error and get the code to run as expected? I've found related error messages through Google searches, but nothing that has allowed me to resolve the issue.</p>
  
  <p>For what it's worth, I can open a Chrome Webdriver without issue by changing the second line of the above to <code>driver = webdriver.Chrome()</code>.</p>
  
  <p>I'm using Python 2.7, Selenium 2.35.0 (I just ran "pip install selenium --upgrade) and Firefox 26.0 on a Windows 8 machine. Any tips or advice others can offer are most appreciated.</p>