Release Process

Because of h2’s place at the bottom of the dependency tree, it is extremely important that the project maintains a diligent release schedule. This document outlines our process for managing releases.


h2 follows semantic versioning of its public API when it comes to numbering releases. The public API of h2 is strictly limited to the entities listed in the h2 API documentation: anything not mentioned in that document is not considered part of the public API and is not covered by the versioning guarantees given by semantic versioning.


h2 has the notion of a “release series”, given by a major and minor version number: for example, there is the 2.1 release series. When each minor release is made and a release series is born, a branch is made off the release tag: for example, for the 2.1 release series, the 2.1.X branch.

All changes merged into the master branch will be evaluated for whether they can be considered ‘bugfixes’ only (that is, they do not affect the public API). If they can, they will also be cherry-picked back to all active maintenance branches that require the bugfix. If the bugfix is not necessary, because the branch in question is unaffected by that bug, the bugfix will not be backported.

Supported Release Series’

The developers of h2 commit to supporting the following release series:

  • The most recent, as identified by the first two numbers in the highest version currently released.
  • The immediately prior release series.

The only exception to this policy is that no release series earlier than the 2.1 series will be supported. In this context, “supported” means that they will continue to receive bugfix releases.

For releases other than the ones identified above, no support is guaranteed. The developers may choose to support such a release series, but they do not promise to.

The exception here is for security vulnerabilities. If a security vulnerability is identified in an out-of-support release series, the developers will do their best to patch it and issue an emergency release. For more information, see our security documentation.