Crap, while I've already done the upgrade I wanted to see the presentation, however, I have a sprint wrapup meeting... I'll have to catch it once the video is released. @sergiodelamo While I know what I've done to work around the Proxies not being unwrapped anymore, I would be interested to hear, what the best practices are around dealing with that. Upgrading to Grails 4 was way easier then upgrading to 3.3, the only issues I really ran into were the proxy issue and some legacy queries that used positional ? variables.