Server: Raspberry Pi 3
OS: Dietpi - version 159
Geckodriver version: 0.22 for arm
Firefox version: 52.9.0
Python version: 3.5
Selenium version: 3.14.1 <
If you are running Firefox on a system with no display, make sure you use headless mode.
from selenium import webdriver
from selenium.webdriver.firefox.options import Options
options = Options()
options.headless = True
driver = webdriver.Firefox(options=options)
Also, make sure you have compatible versions of Firefox, Selenium, and Geckodriver: https://firefox-source-docs.mozilla.org/testing/geckodriver/Support.html