Reposted from the Core group on groups.drupal.org

In preparation for the minor release, Drupal 9.1.x will enter the alpha phase the week of October 19th, 2020. Core developers should plan to complete changes that are only allowed in minor releases prior to the alpha release. The 9.1.0-alpha1 deadline for most core patches is October 16. (More information on alpha and beta releases.)

• Developers and site owners can begin testing the alpha after its release.

• The 9.2.x branch of core will be created, and future feature and API additions will be targeted against that branch instead of 9.1.x. All outstanding issues filed against 9.1.x will be automatically migrated to 9.2.x.

• Once 9.2.x is branched, alpha experimental modules will be removed from the 9.1.x codebase (so their development will continue in 9.2.x only). The Config Environment module is an alpha stability module in 9.1.x.

• All issues filed against 9.0.x will then be migrated to 9.1.x, and subsequent bug reports should be targeted against the 9.1.x branch.

• During the alpha phase, core issues will be committed according to the following policy:

  1. Most issues that are allowed for patch releases will be committed to 9.1.x and 9.2.x.
  2. Most issues that are only allowed in minor releases will be committed to 9.2.x only. A few strategic issues may be backported to 9.1.x, but only at committer discretion after the issue is fixed in 9.2.x (so leave them set to 9.2.x unless you are a committer), and only up until the beta deadline.

Drupal 8.9.0-beta1 will be released the week of November 2nd

Roughly two weeks after the alpha release, the first beta release will be created. All the restrictions of the alpha release apply to beta releases as well. The release of the first beta is a firm deadline for all feature and API additions. Even if an issue is pending in the Reviewed & Tested by the Community (RTBC) queue when the commit freeze for the beta begins, it will be committed to the next minor release only.

The release candidate phase will begin the week of November 16th. See the summarized key dates in the release cycle, allowed changes during the Drupal 8 and Drupal 9 release cycles, and Drupal 8 and 9 backwards compatibility and internal API policy for more information.

The scheduled release date of Drupal 9.1.0 is December 2nd, 2020.

Bugfix and security support of Drupal 9.0.x, 8.8.x and 8.9.x.

Security coverage for Drupal 8 and 9 is generally provided for the previous minor release as well as the newest minor release. However, Drupal 8.9.x is a Long-Term Support release where support is provided until November 2021. Based on these the following changes are upcoming: