As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON CLIMB HYDRAULIC RESERVOIR LOW LEVEL ECAM MESSAGE OBSERVED. FLIGHT RETURNED TO DEPARTURE BASE. MAINTENANCE ACTION FOUND QUICK DISCONNECT FITTING ON YELLOW PTU MANIFOLD LEAKING AT "B" NUT. NEW "O" RING INSTALLED AND GREEN SYSTEM HYDRAULIC FLUID REPLENISHED.