As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON GEAR RETRACTION AFTER TAKEOFF, CREW RECEIVED AMBER HYDRAULIC A LEVEL LOW (HYD A LVL LOW) MESSAGE WITH 0 QUANTITY INDICATED. CHECK LIST FOLLOWED, EMERGENCY DECLARED, AND UNSCHEDULED LANDING AT ALTERNATE AIRPORT PERFORMED WITHOUT INCIDENT. MAINTENANCE EVALUATION FOUND RIGHT MAIN LANDING GEAR ACTUATOR RETRACT HYD FLEX LINE BURST. HYD FLEX LINE WAS REMOVED AND REPLACED. P/N OFF S3128C0124-000G P/N ON AS115-06K0106