As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3948 -PRESS- DUE TO CABIN ALTITUDE ALERT WHILE CLIMBING THROUGH FL240. DESCENDED TO FL100 AND FLIGHT CONTINUED. CORRECTIVE ACTION: MAINTENANCE FOUND APU BLEED DUCT SEAL CLAMP MISSING. REATTACHED SEAL PER B737 AMM 21-00. PERFORMED PACK OPS CHECK PER B737 AMM 21-00-05. OPS CHECK NORMAL.