September 3, 2026
Point a Drupal 10.6 site at Drupal 11.2, run the database updates, and the upgrade stops. Core refuses it. The route from the largest Drupal 10 cohort to most of Drupal 11 does not exist, and the version that does work, 11.3, happens to be the exact version Drupal 12 requires. One number answers both questions. Most 2026 upgrade plans have a different one written into them.
