title: Selenium 3.0.2 error with Firefox 50: executable may have wrong permissions
body: <p>I'm trying to use Selenium 3.0.2 with Firefox 50.0.1 in Windows 7. I've followed the instructions in <a href="https://stackoverflow.com/questions/39312903/running-webdriver-with-firefox-python">this</a> post to setup correctly the driver and the paths but I'm getting the following error: </p>
  
  <pre><code>Traceback (most recent call last):
    File "ixps-bgp.he.net.py", line 38, in &lt;module&gt;
      browser = webdriver.Firefox(firefox_binary=binary,capabilities=caps, executable_path='&lt;path to gecko driver&gt;')
    File "C:\Users\&lt;myusername&gt;\AppData\Local\Continuum\Anaconda2\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 140, in __init__
      self.service.start()
    File "C:\Users\&lt;myusername&gt;\AppData\Local\Continuum\Anaconda2\lib\site-packages\selenium\webdriver\common\service.py", line 86, in start
      os.path.basename(self.path), self.start_error_message)
  selenium.common.exceptions.WebDriverException: Message: '' executable may have wrong permissions.
  
  Exception AttributeError: "'Service' object has no attribute 'process'" in &lt;bound method Service.__del__ of &lt;selenium.webdriver.firefox.service.Service object at 0x00000000023BA240&gt;&gt; ignored
  </code></pre>
  
  <p>Even when I try to execute the script as administrator I still get the error above. I'm using the latest version of the gecko driver (0.13) and I tried both the 64-bit and 32-bit versions. Is this a known issue with any of the current versions?</p>