SpaceX had a successful launch, orbit insertion, and recovery of all 3 rocket boosters last Thursday. Unfortunately, they were unable to fasten down the central core on the ASDS (Autonomous spaceport drone ship) "Of Course I Still Love You:
Shifting seas and high winds brought it down.
(Score: 0) by Anonymous Coward on Tuesday April 16 2019, @01:34PM
The video explains it at one point.
The side boosters, being the first stage to separate, are close enough, moving slow enough, and have enough fuel to turn around and head back to land. The central core, which separates later in the launch, is further away and is traveling too fast to be able to turn around and make it back to land, so a barge is the only feasible means of recovery.