Hi I just saw the actual Katalon version (5.9) includes Selenium 3.7.1 (output on console when executing TestSuite)
This could propably be a reason for the browser can’t start problem. With geckodriver v0.19 I didn’t had those errors and since a new release with geckodriver v0.23 the error appears.
So I replaced v0.23 with v0.20 (v0.19 didn’t work) and it seems to work
Can somebody verify this? If yes Selenium propably should replaced in the new version