August 1, 2022
Drupal 9.3.21 is available and includes backwards-compatible improvements. This is a patch version of Drupal 9.3 and is available for use on production sites. Drupal 9.3 was released in December 2021. From Drupal 9.3, PHP version 8.0 or higher is recommended; PHP 7.3 and higher remains supported. Drupal 9.3 will receive security coverage until December 8, 2022 when Drupal 9.5.0 is released.
Drupal 9 sites on Pantheon use Integrated Composer, enabling one-click core updates through the Dashboard. To check for available updates, click Check Now from the site Dashboard Dev tab.