Following document is meant to align expectations on the upgrade process between major versions.
We only support features and APIs which have been documented in this present documentation. Any other feature/API change will not be considered a breaking change.
We use semantic versioning, and thus you MUST expect breaking changes between major versions (REST API, programmatic APIs, templates, data models etc). We will document these breaking changes in the release notes, and do our best to provide automatic upgrades if possible.
You MUST expect the upgrade process to be an offline process that requires the production system to be offline during the entire upgrade process. We strive allow online rolling upgrades in the future, but we are not there yet.