Selenium Python in firefox browser: self.session_id = response['sessionId'] KeyError: 'sessionId'

[Edward Alexander]

I am running a simple test on selenium .The following is displayed on Pycharm console

C:\Python36\python.exe C:/Users/Edward.Alexander/PycharmProjects/DaveHunt/tests/heroku.py

Traceback (most recent call last):

  File "C:/Users/Edward.Alexander/PycharmProjects/DaveHunt/tests/heroku.py", line 2, in <module>

    driver = webdriver.Firefox()

  File "C:\Python36\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 150, in __init__

    keep_alive=True)

  File "C:\Python36\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 92, in __init__

    self.start_session(desired_capabilities, browser_profile)

  File "C:\Python36\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 180, in start_session

    self.session_id = response['sessionId']

KeyError: 'sessionId'

   How can i solve this problem

[Andreas Tolfsen]

Without knowing which versions of Selenium, Firefox, and geckodriver
you’re using, it’s hard to tell what would cause this. My best
advice is to verify this again with the latest versions available.

As Selenium, Firefox, and geckodriver are moving through a transition
phase to become specification conforming, you may experience
compatibility fallouts.