Has anyone ever found a way to stop a Mass update that is in progress? We had one kicked off last night by mistake that we would have like to stop in progress?

oof No - outside of one that was using a script that I deleted the script. You could potentially put something in place to cause an error with the context of Mass Update (maybe workflow/script?) to just cause them to bomb in the meantime

That might do it. Something to keep in mind for next time for sure.