As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED AN APU OIL CAUTION MESSAGE IN FLIGHT. CREW ELECTED TO DIVERT TO BNA AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND VISUALLY CHECKED THE APU OIL LEVEL AND APU OIL SYSTEM IN ACCORDANCE WITH THE AIRCRAFT MAINTENANCE MANUAL. OIL LEVEL CHECKED GOOD, NO VISUAL DEFECTS NOTED AT THIS TIME. AIRCRAFT WAS RELEASED FOR SERVICE.