Falcon lands on drone ship, but the lockout collet [a metal sleeve] doesn't latch on one [of] the four legs, causing it to tip over post landing. (dotearth.blogs.nytimes.com)
The center core then broke away from the vehicle's upper stage, but did not land as intended on one of SpaceX's autonomous drone ships in the Atlantic Ocean. (theverge.com)
It is one of two robotic drone ships used by SpaceX for its rocket landing attempts, the second of which is named «Just Read the Instructions.» (scientificamerican.com)