Serial.readBytesUntil()

Man this guy is awfully combative. Why don't you just leave him alone and let him learn by himself and with Google. He obviously doesn't want to be taught anything here.

OP: why do you keep posting here if you don't want to learn anything? There's another section called gigs and collaborations where you can pay someone to just fix your code without worrying about people trying to help you learn to do it on your own.