问如何解决Selenium Python newSession错误？

EN

from selenium import webdriver
driver = webdriver.Firefox()

---------------------------------------------------------------------------
WebDriverException                        Traceback (most recent call last)
<ipython-input-7-a807687b0e15> in <module>()
----> 1 driver = webdriver.Firefox()

~\AppData\Local\Continuum\anaconda3\lib\site-packages\selenium\webdriver\firefox\webdriver.py in __init__(self, firefox_profile, firefox_binary, timeout, capabilities, proxy, executable_path, options, service_log_path, firefox_options, service_args, desired_capabilities, log_path, keep_alive)
    172                 command_executor=executor,
    173                 desired_capabilities=capabilities,
--> 174                 keep_alive=True)
    175 
    176         # Selenium remote

~\AppData\Local\Continuum\anaconda3\lib\site-packages\selenium\webdriver\remote\webdriver.py in __init__(self, command_executor, desired_capabilities, browser_profile, proxy, keep_alive, file_detector, options)
    155             warnings.warn("Please use FirefoxOptions to set browser profile",
    156                           DeprecationWarning, stacklevel=2)
--> 157         self.start_session(capabilities, browser_profile)
    158         self._switch_to = SwitchTo(self)
    159         self._mobile = Mobile(self)

~\AppData\Local\Continuum\anaconda3\lib\site-packages\selenium\webdriver\remote\webdriver.py in start_session(self, capabilities, browser_profile)
    250         parameters = {"capabilities": w3c_caps,
    251                       "desiredCapabilities": capabilities}
--> 252         response = self.execute(Command.NEW_SESSION, parameters)
    253         if 'sessionId' not in response:
    254             response = response['value']

~\AppData\Local\Continuum\anaconda3\lib\site-packages\selenium\webdriver\remote\webdriver.py in execute(self, driver_command, params)
    319         response = self.command_executor.execute(driver_command, params)
    320         if response:
--> 321             self.error_handler.check_response(response)
    322             response['value'] = self._unwrap_value(
    323                 response.get('value', None))

~\AppData\Local\Continuum\anaconda3\lib\site-packages\selenium\webdriver\remote\errorhandler.py in check_response(self, response)
    240                 alert_text = value['alert'].get('text')
    241             raise exception_class(message, screen, stacktrace, alert_text)
--> 242         raise exception_class(message, screen, stacktrace)
    243 
    244     def _value_or_default(self, obj, key, default):

WebDriverException: Message: newSession