Mine is with Project server as the thing that stands out in my head, I learned that when you are doing a migration/ upgrade, the best way to attach your 4 Project server Databases (Draft, Published, Archived, Reporting) is to just create a PWA site with the default databases, and when it competes, go back in and edit the PWA instance. When you get back in Change the names of the 4 Databases to match your old ones, and it will expect data in there this time, and allow you to attach your Project databases.

Come let’s hear what you got, this could help someone out there searching google for something to help them with something they are doing.