(Urgent issue that need to be solved within 2 hours) selenium chromedriver suddenly not working : seesion not created exception : My code, which used to work until yesterday, suddenly stopped working. I'd been running codes from jupyter notebook to auto-collect repeating data from a webpage. It is as follows(url is changed to google for privacy reasons):

    # use selenium to start Chrome session to open a certain page 
    dr = webdriver.Chrome()
    dr.get("http://www.google.com")

The error message I got:

    ---------------------------------------------------------------------------
    WebDriverException                        Traceback (most recent call last)
    <ipython-input-25-84be89301b0d> in <module>()
          1 # use selenium to start Chrome session to open google. 
    ----> 2 dr = webdriver.Chrome()
          3 dr.get("http://www.google.com")
    
    /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/chrome/webdriver.py in __init__(self, executable_path, port, chrome_options, service_args, desired_capabilities, service_log_path)
         65                 command_executor=ChromeRemoteConnection(
         66                     remote_server_addr=self.service.service_url),
    ---> 67                 desired_capabilities=desired_capabilities)
         68         except:
         69             self.quit()
    
    /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py in __init__(self, command_executor, desired_capabilities, browser_profile, proxy, keep_alive)
         85         self.error_handler = ErrorHandler()
         86         self.start_client()
    ---> 87         self.start_session(desired_capabilities, browser_profile)
         88         self._switch_to = SwitchTo(self)
         89         self._mobile = Mobile(self)
    
    /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py in start_session(self, desired_capabilities, browser_profile)
        139             desired_capabilities['firefox_profile'] = browser_profile.encoded
        140         response = self.execute(Command.NEW_SESSION, {
    --> 141             'desiredCapabilities': desired_capabilities,
        142         })
        143         self.session_id = response['sessionId']
    
    /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py in execute(self, driver_command, params)
        199         response = self.command_executor.execute(driver_command, params)
        200         if response:
    --> 201             self.error_handler.check_response(response)
        202             response['value'] = self._unwrap_value(
        203                 response.get('value', None))
    
    /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/errorhandler.py in check_response(self, response)
        179         elif exception_class == UnexpectedAlertPresentException and 'alert' in value:
        180             raise exception_class(message, screen, stacktrace, value['alert'].get('text'))
    --> 181         raise exception_class(message, screen, stacktrace)
        182 
        183     def _value_or_default(self, obj, key, default):
    
    WebDriverException: Message: session not created exception
    from unknown error: Runtime.executionContextCreated has invalid 'context': {"auxData":{"frameId":"7600.1","isDefault":true},"id":1,"name":"","origin":"://"}
      (Session info: chrome=54.0.2840.71)
      (Driver info: chromedriver=2.20.353124 (035346203162d32c80f1dce587c8154a1efa0c3b),platform=Mac OS X 10.11.6 x86_64)

Can anyone help? I really have no idea how to solve this and why I'm suddenly getting this message. And it's quite urgent. Thanks in advance.