Click chemistry, a term used to describe a number of high yield reactions, is used far and wide by chemists. The azide alkyne Huisgen cycloaddition typifies click chemistry and awhile back, I described it as my favorite reaction. In my heartfelt description of my favorite reaction, I described some recent research reported in Nature about an “unclick” reaction. Having an unclick reaction opened up many new options for click chemistry and was a very exciting development for the field. Unfortunately, doubts are now surfacing as to the validity of this research. Bethany Halford at Chemical and Engineering News has written a great summary of the controversy.