As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: IN CRUISE THE APU LOW OIL PRESSURE LIGHT ILLUMINATED, AND APU AUTO SHUTDOWN OCCURRED. FLIGHT DIVERTED BACK TO MSP, LANDING SAFELY. REPLACED APU OIL PRESSURE SWITCH PER AMM 49-94-22. SERVICED APU PER AMM 12-13-31. ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK.