As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) APU OIL TEMP CAUTION MESSAGE IN FLIGHT. QRH DIRECTED TO LAND AT NEAREST SUITABLE AIRPORT IF UNABLE TO SHUTOFF APU. DIVERTED. APU NEVER SHUT DOWN AS EXPECTED WITH OIL TEMP CAUTION, REQUIRED MANUAL SHUTDOWN AT GATE. CORRECTIVE ACTION: REMOVED AND REPLACED APU OIL COOLER. (TC# 20190611011)