ERROR 404 OOPS! Looks like little Reggie is at it again. We can't seem to find the page you are looking for. Check the links below for content you might find helpful. discussion Exercise: Adding Default Data Transforms (: Invalid expression or reference: List/group error) question Getting Invalid expression or reference error in Data-Transform rule question Getting Source— Invalid expression or reference: error while saving Data Transform discussion Invalid Expression when adding Boolean Expression in Pega Robot Studio question Boolean Expression invalid Search Pega Community Ask Pega Community