Upgrading from Vue 2 to Vue 3
According to the Vue roadmap, Vue 2 will only get one more minor release as an LTS version, supported for 18 months. This was back in September 2020, which means that a lot of Vue 2 projects will either have to switch to the migration build or to Vue 3 to ensure an up-to-date frontend framework.
Since it is a major upgrade, Vue 3 comes with breaking changes. First of all, Vue provides a migration build that should help with the transition to Vue 3, as it is compatible with Vue 2 while providing Vue 3 support.