New player having trouble with Proficient Skill rolls

Everytime I click on one of the skills for a roll (including Tool Proficiencies) the chat returns with  SyntaxError: Expected ",", ".", "[", "d", "e", "t", "}", [ |\t], [+|\-|*|\/|%] or [0-9] but "r" found. I have no idea what is going on... I have tried reading other posts with the same problem but got no luck. I am new to Roll20 (not really new, but unexperienced) and I have no clue in how to assess this problem.

Assuming this is on the official 5e sheet by Roll20, it would be good to see a screenshot of your sheet, it is likely that there is a field missing some info or containing an illegal (ie non-numerical) character... an 'r' in this case. It could be something else but that would be a good start for diagnosing the issue :)