Hi,
After performing many Geodatabase Upgrades for many instances over the the past few years, i find the "Upgrade Pre-Requisite Check " tool usless in terms of detecting real upgrade problems.
Many times the tool runs and states that your geodatabase is fine and ready for upgrade, and when your perfom the REAL upgrade ....BOOM... actual problems shows up !!!!.
This is usless when you want to prepare for a PRODUCTION upgrade, since you don't want to be stucked with complicated problems in production, and the only option you have is "restore" and your scheduled upgrade is failed.
from my observation the Pre-Requisite Check tool checks (privileges, orphan objects,domains....) but it doesn't go deeper in analysis.
please share your experience and openions.......
Cheers