Prepare to Migrate to Drupal 9 on Pantheon

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This overview outlines the steps to prepare an existing Drupal site for upgrade or migration to Drual 9 with Integrated Composer.

Test an Existing Drupal Site for Drupal 9 Upgrade Compatibility

  1. Upgrade to the latest Drupal 8.9 release.

    • Although Drupal supports upgrading to Drupal 9 from Drupal 8.8, ensure that your site is on the latest Drupal 8.9 release before trying Drupal 9 on Pantheon.
  2. Review the How to Prepare Your Drupal 7 or Drupal 8 Site for Drupal 9 guide on

  3. Use the Upgrade Status Drupal 8/9 module to generate a full report of your site’s compatibility.

  4. Help contributed modules prepare for Drupal 9, for example by updating modules' deprecated API usages and converting tests to PHPUnit.

  5. Check out Acquia’s Drupal 9 Deprecation Status Upgrade Tracker for information about Drupal 9 support for contributed Drupal modules and themes.

Update Deprecated Code for Drupal 9 Compatibility

Drupal 9 has deprecated a number of different functions and APIs in favor of better options going forward.

For example, node_load() was replaced in Drupal 9 with Node::load resulting in this change needed:

Drupal 8:

$node = node_load(1);

Drupal 9:

use \Drupal\node\Entity\Node;
$node = Node::load(1);

Since most of these changes are relatively minor, there are a number of deprecation checking and correction tools available.