As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 390 AND .77M ATC REQUESTED TO SLOW TO .75M. ALMOST IMMEDIATELY GOT NR 1 LEFT BLEED TRIP. LOST CABIN PRESS CABIN WENT UP TO 12'000 TO 12'200. BEFORE BLEED RESET WORKED AT APPROX 29'000. LEVELED AT FLT 250 AND KEPT AS STABLE AS POSSIBLE. NO FURTHER TRIPS OCCURRED. MTC IN PROGRESS DNTC. REPLACED 390 DEG TEMP SENSOR ON NR 1 ENG PYLON. REPLACED 390 DEG TEMP SENSOR NR 2 ENG PYLON. CKS GOOD PER M/M.