We had an issue upgrading from 7.1.9 (b6423) to 7.2.1 (b6516).
Everything seemed to go fine during the upgrade using the .gpkg in the upgrades directory. We could login to the gateway fine with our credentials. When opening a client we had an issue as the screen just hung after entering the security information and pressing login. We are using AD/Internal hybrid authentication. When logging into the designer we could authenticate, however, bringing up a project we were greeted by an Uncaught AbstractMethodError.
We tried reinstalling with the windows installer and had the same issue. We then tried to restore a manual gateway backup and that also had the same results. Before trying to roll back to 7.1.9 we decided to try 7.2.2-beta2 and all seems fine. In fact one of the clients that was sitting hung actually completed the startup.