Trivial is not the word I would use. My 2 -> 3 migration is a currently ongoing nightmare, even with the compat lib. I was using vue-class-component with typescript, which apparently... just doesn't work at all with Vue 3? And this isn't really documented, so I basically spent today digging around in Vue's guts with the debugger to prove there was no good way to salvage it for my code, I really just needed to rip it out to have a chance of running it at all. Hopefully that was the worst of it, but Vuex is still acting up. Thank god for VCS or this would be terrifying.