Usher wasn't at the One Love Manchester concert for two very good reasons -- his son needed him and, more to the point, he wasn't ever scheduled to perform at the concert.
Usher says Sunday was his son's first day at a camp for kids with diabetes. As he put it, "This was an important day for him and for myself as a proud father." He added ... "Stay strong UK."
As for why everyone was expecting him to be at the show -- a UK publicist for the concert initially announced Usher and David Beckham would be "making appearances." We're told that was a reference to recorded messages both made, which were played during the concert ... and NOT live performances or appearances.
The publicist eventually took their names off the list, but by that point ... word had spread.
Still, Usher said ... "So happy to see that last night's concert in Manchester proved that love always prevails."