在使用Python2.7+Selenium3.0.2+Firefox50.1时，鼠标事件ActionChains运行总是报错，报错信息如下：
C:\Python36\python3.exe C:/Users/root/PycharmProjects/untitled3/test170117.py
Traceback (most recent call last):
File "C:/Users/root/PycharmProjects/untitled3/test170117.py", line 458, in <module>
ActionChains(driver).move_to_element(set).perform()
File "C:\Python36\lib\site-packages\selenium\webdriver\common\action_chains.py", line 74, in perform
action()
File "C:\Python36\lib\site-packages\selenium\webdriver\common\action_chains.py", line 225, in <lambda>
Command.MOVE_TO, {'element': to_element.id}))
File "C:\Python36\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 236, in execute
self.error_handler.check_response(response)
File "C:\Python36\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 192, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: POST /session/3ba988a1-5c6f-4999-8815-71d40e62a6af/moveto did not match a known command
经过搜索，说是geckodriver和Firefox有Bug,最后将Selenium3.0.2换成Selenium2.53.0（此时环境为Python2.7+Selenium2.53.0+Firefox50.1），此时运行python脚本时，报错：
报错信息忘了截图了？？？？？
搜索后，说是因为Selenium支持Firefox及其以下版本，所以最后环境变为：Python2.7+Selenium2.53.0+Firefox46，问题解决，ActionChains（）类下的各种鼠标操作方法完美运行。
github上该Bug相关信息：
https://github.com/SeleniumHQ/selenium/issues/2285
https://github.com/mozilla/geckodriver/issues/159