New Grails versions are released fairly often, and they always contain bug fixes and new features that you probably want to have available in your applications and plugins. You might not be able to upgrade for every release, but you shouldn’t get too far out of date. We try our best to limit breaking changes and other changes that will make upgrading harder, but sometimes progress has its costs.
Grails does have an upgrade script, but it doesn’t do all of the work needed to upgrade between versions, and will likely be removed or at least renamed in a future version of Grails, because the name is a bit misleading. It is useful in some respects, but there will always be manual steps involved in upgrading to a newer version of Grails.
So what does the upgrade script do? There are a few fixes for very old (pre-1.0) applications:
and there are fixes for all versions: