That core booster approached the platform as planned, but it unfortunately hit the water going 300 MPH and was lost, because some of its return engines failed to light. Video feeds of the attempted landing cut out upon approach, and in the live stream SpaceX provided of the launch, you could hear someone say “We’ve lost the core” but it wasn’t clear whether that indicated just the feed, or the booster itself.

2/3 ain't good enough. They'll keep at it though, the landing of the two other boosters was great.