Beware the lotus.domino.UserID error in Domino 9.0.1 FP8/FP9 and other upgrade musings 

By Michael G. Smith | 11/30/17 1:17 PM | App Dev - XPages | Added by Oliver Busse

Over the weekend we upgraded our production Domino servers to get to 9.0.1 FP9 HF139(64-bit) & HF137 (32-bit). Well, we “tried” to upgrade the servers. Then all hell broke loose.