The Tor Browser updated to 7.5.6. The previously working code failed with
InvalidSessionIdException:
After updating to marionette_driver 2.7, the call to client.start_session() failed with
marionette_driver.errors.UnknownCommandException: WebDriver:NewSession
Which version of the marionette_driver should be used with this Firefox version? (Or maybe another framework like Selenium?)
Since there are only a few version at Pypi, and no other answer seems to exist, just try them all starting with the current one.
It worked with version 2.5:
pip2 install marionette_driver==2.5
UPDATE: The InvalidSessionIdException returned. To fix this, call client.start_session() again (it can be called when catching the exception in a try-block)