How can I switch from a beta version to a stable release ?
over topics on the same subject :
Or Howto migrate my beta site to the next stable release ?
What's your beta version? It's safe to upgrade to the version upper than now. You can upgrade any 1.2.x.beta or 1.3.x.beta to 1.3 stable.
Change app.yml version from "tests-passed" to "stable".
Thanks all. Here a nice HOWTO for upgrading a docker install