As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRFT RETURNED TO BOS. DUIRNG CLIMBOUT GREEN HYDRAULIC SYSTEM RESEVOIR LOW LEVEL ECAM MESSAGE ILLUMINATED. THE AIRCRAFT LANDED AT BOS WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND FORWARD PRESSSURE SUCTION / CASE DRAIN RETURN PIPE LEAKING IN THE LEFT PYLON AND REPLACED IT PER AMM 29-11-49