As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DECLARED EMER, CABIN ALTITUDE WARNING AT FL400. PERFORMED AN EMER DECENT. GOT CONTROL OF PRESS PASSING 14000 FT. BEFORE DECENT DIFFERENTIAL PRESS WAS 5.8 PSI & CABIN ALTITUDE WAS 9500 FT. FOUND FLEX SEAL IN RT PACK BAY AT PRESS BULKHEAD BLOWN. R & R FLEX SEAL IAW MM.