What was found
CREW RECEIVED A BLEED 2 OVERPRESSURE MESSAGE. NOTED THAT THE CABIN PRESSURE WAS CLIMBING FOLLOWED BY A CABIN ALTITUDE HIGH WARNING MESSAGE. DONNED OXYGEN MASKS AND BEGAN DECENT TO 10000 FEET WHERE CABIN ALTITUDE STABILIZED, BUT THEN BEGAN GOING UP AGAIN. DECLARED AN EMERGENCY, DIVERTED, AND LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE NR 2 AMS CONTROLLER SPA SLOT 20 AND NR 2 NAPRSOV IAW AMM AND OPS CHECKED GOOD.