pythonのwebdriverでfirefoxを使う際にエラーが出てしまう

リモート先のArchLinuxからpythonのwebdriverでfirefoxを使ってスクレイピングをしようとしたのですが、以下のようなエラーが出てうまくいきませんでした。

 開発環境

Arch linux
python 3.6

 コマンド

sudo pacman -Sy --noconfirm unzip icu xorg-server-xvfb &&
sudo pacman -Sy --noconfirm firefox &&
wget https://github.com/mozilla/geckodriver/releases/download/v0.21.0/geckodriver-v0.21.0-linux64.tar.gz -O g.tar.gz &&
yes|tar -zxvf g.tar.gz &&
rm -rf g.tar.gz &&
pip3 install selenium &&
pip3 install pyvirtualdisplay &&
python3 scrape.py

`

 ソースコード

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
from pyvirtualdisplay import Display
from time import sleep

if __name__ == "__main__":
    display = Display(visible=0, size=(1024, 768))
    display.start()

    binary = FirefoxBinary("/usr/sbin/firefox")
    binary.add_command_line_options("-headless")
    cap = DesiredCapabilities().FIREFOX.copy()
    cap["marionette"] = False
    cap["firefox_binary"] = "/usr/sbin/firefox"
    driver = webdriver.Firefox(
        firefox_binary=binary,
        executable_path="./geckodriver", capabilities=cap)

    driver.get("https://www.google.com/")
    driver.close()
    display.stop()

 エラー文

Traceback (most recent call last):
  File "scrape.py", line 12, in <module>
    driver = webdriver.Firefox(executable_path="./geckodriver", capabilities=cap)
  File "/usr/lib/python3.6/site-packages/selenium/webdriver/firefox/webdriver.py", line 184, in __init__
    self.binary, timeout)
  File "/usr/lib/python3.6/site-packages/selenium/webdriver/firefox/extension_connection.py", line 52, in __init__
    self.binary.launch_browser(self.profile, timeout=timeout)
  File "/usr/lib/python3.6/site-packages/selenium/webdriver/firefox/firefox_binary.py", line 73, in launch_browser
    self._wait_until_connectable(timeout=timeout)
  File "/usr/lib/python3.6/site-packages/selenium/webdriver/firefox/firefox_binary.py", line 104, in _wait_until_connectable
    "The browser appears to have exited "
selenium.common.exceptions.WebDriverException: Message: The browser appears to have exited before we could connect. If you specified a log_file in the FirefoxBinary constructor, check it for details.

 追記

sudo pacman -Sy --noconfirm firefox firefox-adblock-plus firefox-noscript を実行することで上記のエラーは起こらなくなったのですが、代わりに以下のようなエラーが出るようになりました。このエラーの解決方法をご教授ください。

 エラー文

selenium.common.exceptions.WebDriverException: Message: Can't load the profile. Possible firefox version mismatch. 
You must use GeckoDriver instead for Firefox 48+. Profile Dir: /tmp/tmpvwp6fuam 
If you specified a log_file in the FirefoxBinary constructor, check it for details.