Branching of the docs for a new major LTS version

Create branches for the new LTS version in all versioned official repositories

This includes all manuals in the "All Documentation" menu with version hints, excluding the System extension manuals. The System extension manuals will receive their new versions automatically via webhook in the release. This might take a few days.

Create a new branch. 14.3 in this example.
Limit the composer.json to that version. For example "typo3/cms-core": "^14.3" instead of "typo3/cms-core": "dev-main as 14.3" and make sure composer update works.

Set the release and version to the new minor version, for example

Documentation/guides.xml

<project title="TYPO3 Explained"
         release="14.3"
         version="14.3"
         copyright="since 2012 by the TYPO3 contributors"
/>

After all the new LTS branches have been created and rendered for all repositories, revisit the guides.xml in all new LTS branches and raise to the preferred typo3 version:

Documentation/guides.xml

<extension
    class="\T3Docs\Typo3DocsTheme\DependencyInjection\Typo3DocsThemeExtension"
    project-home="https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/"
    project-contact="https://typo3.slack.com/archives/C028JEPJL"
    project-repository="https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-CoreApi"
    project-issues="https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-CoreApi/issues"
    edit-on-github-branch="main"
    edit-on-github="TYPO3-Documentation/TYPO3CMS-Reference-CoreApi"
    typo3-core-preferred="14.3"
    interlink-shortcode="t3coreapi"
/>

We usually leave the edit-on-github-branch on main to avoid people making PRs against the LTS branch and to avoid confusion in our backport workflows.

Add new eLTS warnings to the newly created eLTS version

Add a warning to the Documentation/Includes.rst.txt of the branch for the new eLTS versions of all repositories:

Documentation/Includes.rst.txt

..  You can put central messages to display on all pages here

..  attention::
    TYPO3 v12 has reached end-of-life as of April 30th 2026 and
    is no longer being maintained. Use the version switcher on the top
    left of this page to select documentation for a supported version of TYPO3.

    Need more time before upgrading?
    You can purchase Extended Long Term Support (ELTS) for TYPO3 v12 here:
    `TYPO3 ELTS <https://typo3.com/services/extended-support-elts>`__.

Update the start page docs.typo3.org for a new major version

Add the new major version to the main menu: https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/Documentation/_mainMenu.rst.txt Remove the versions that are now ELTS.
Add the new API version to the main menu
Require the latest LTS version in https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/composer.json

Update api.typo3.org for a new major version

Add the new TYPO3 LTS version for rendering into https://github.com/TYPO3-Documentation/t3docs-ci-deploy/blob/main/.github/workflows/api-typo3-org.yml#L13
Add the new TYPO3 version to the sidebar of api.typo3.org: https://github.com/TYPO3-Documentation/render-guides/blob/main/packages/typo3-api/template/components/sidebar.html.twig#L9
Trigger rendering of the API by running the workflow above
Add the new version to the api.typo3.org start page: https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/WebRootResources-api.typo3.org/index.html
Add the new version to the main menu: http://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/Documentation/_mainMenu.rst.txt

Set the "stable" version for links to the new LTS version in renderguides

You should only do this after all versioned repositories exist in the new LTS version and have been rendered; otherwise, rendering links will fail in all manuals that are newly rendered. Then create a new renderguides release by creating a tag for the version. See https://github.com/TYPO3-Documentation/render-guides/pull/1246 for an example.

Make the new LTS version the preferred result in the docs search

Require the newly created version of t3docs/typo3-version-handling (created by the renderguides release in https://github.com/TYPO3-Documentation/t3docs-search-indexer) and make a new release of the search.