What was found
BOTH LEFT AND RIGHT AUTO CABIN PRESSURE CONTROLLERS INOP. EICAS CABIN ALT AUTO MESSAGE RECEIVED. BOTH LT & RT ASCPC (AIR SUPPLY & CABIN PRESSURE CONTROLLER) FAILED DUE TO INTERNAL FAULT. BOTH ASCPC'S LOST PRIMARY CONTROL RESULTING IN CABIN PRESSURE CONTROL SYSTEM ON MANUAL CONTROL. BOTH ASCPC WERE REPLACED, AND A/C RETURNED TO REVENUE SERVICE WITHOUT FURTHER INCIDENT. HONEYWELL IS RELEASING A NEW ASCPC SOFTWARE UPGRADE TO FIX THIS PROBLEM SB 1151100-36-39, BOEING SB 777-36-0013.