Pantheon Drupal CMS 2 Upstream: Plan It as a Migration
· 6 min read
Pantheon switched the Drupal CMS upstream to Drupal CMS 2 on March 6, 2026, for new sites only. Existing Drupal CMS sites are not auto-updated and Drupal 10/11 upstream sites are not affected, so a team that reads this as "new upstream, apply everywhere" is about to run a migration by accident.