From what I can see here your Workflow File fails due to an issue with a selector. Maybe try making this “Attach Browser” selector more dynamic? If the selector points towards a browser with a particular title while another one is open, the selector will inevitably fail.
I’m fairly new to this Forum and RPA, but I don’t think it will help you if the answer is provided. Maybe you could share your workflow file so we can point you in the right direction?