I did the vue 3 bump a while back and Evan You did a fantastic commit by commit repo to follow along and there's even a migration build of vue 2 which warns you

I did the vue 3 bump a while back and Evan You did a fantastic commit by commit repo to follow along and there's even a migration build of vue 2 which warns you of all the areas where your app will break in vue 3, really fantastic. I can't claim that that upgrade was painless, it took a few days with an app with > 10 pages, >20 custom components and I had to push ahead with re-writing a 3rd party component or 2 that was only vue 2 at the time (honestly I should never have used them in the first place. reap what you sow). But build times are faster, my bundle size is a lot smaller, I'm really pleased with the new features, and I'm a building faster as a result.