Here is better example showing how to attach to firstly opened FireFox session/instance: #include "wd_helper.au3" #include "wd_capabilities.au3" # HOW TO TEST: ; At first run choose [Yes] to create new session FireFox running instance ; At second run choose [No] to attach to active FireFox running instance # TODO: ; https://github.com/operasoftware/operachromiumdriver/blob/master/docs/desktop.md --remote-debugging-port=port Global $