RedHat 6.8上的Selenium Webdriver+geckodriver+python 2.6.6+Firefox无法打开浏览器

我在使用Selenium Webdriver for python成功启动Firefox浏览器时遇到了问题。我有以下设置参数:

Selenium Webdriver 3.4.3
Python 2.6.6
geckodriver-v0.18.0-linux64.tar.gz
firefox-45.0.1.1.el6.x86_64

现在,geckodriver文件已解压缩,当前处于 /usr/local/bin

rwxrwxrwx. 1 root root 7129173 Jul 26 14:42 geckodriver

我已经更新了 .bash_profile 要将路径包括为:

PATH=$PATH:$HOME/bin:/usr/local/bin/geckodriver

我使用的脚本来自Selenium-3.4.3目录“readme.rst”中的自述文件。

first_selenium_script.py

from selenium import webdriver

browser = webdriver.Firefox()
browser.get('http://seleniumhq.org/')

结果如下:,

Traceback (most recent call last):
  File "first_selenium_script.py", line 3, in <module>
    browser = webdriver.Firefox()
  File "/usr/lib/python2.6/site-   packages/selenium-3.4.3-py2.6.egg/selenium/webdriver/firefox/webdriver.py",   line 152, in __init__
keep_alive=True)
  File "/usr/lib/python2.6/site- packages/selenium-3.4.3-py2.6.egg/selenium/webdriver/remote/webdriver.py", line 98, in __init__
self.start_session(desired_capabilities, browser_profile)
  File "/usr/lib/python2.6/site- packages/selenium-3.4.3-py2.6.egg/selenium/webdriver/remote/webdriver.py", line 188, in start_session
response = self.execute(Command.NEW_SESSION, parameters)
  File "/usr/lib/python2.6/site- packages/selenium-3.4.3-py2.6.egg/selenium/webdriver/remote/webdriver.py", line 256, in execute
self.error_handler.check_response(response)
  File "/usr/lib/python2.6/site-packages/selenium-3.4.3-py2.6.egg/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Unable to find a  matching set of capabilities

有什么想法吗?谢谢。