blunder upon (?.)

• alight upon
• be all thumbs
• blunder
• blunder away
• blunder into
• blunder on
• boggle
• botch
• bumble
• bump into
• bungle
• butcher
• chance upon
• come across
• come on
• come up against
• come upon
• commit a gaffe
• discover serendipitously
• encounter
• fall in with
• faux pas
• flounder
• fumble
• happen upon
• hit upon
• light upon
• lumber
• mar
• meet up with
• meet with
• miscue
• muddle
• muff
• murder
• play havoc with
• run across
• run into
• run up against
• slip
• spoil
• stumble
• stumble on
• stumble upon
• trip
• tumble on