Developers

Upgrading to Drupal 10 from Drupal 9

The following information is currently targeted to those site admins who have a site built on a custom theme implementation or have written custom modules for Drupal 9.

If you are using the standard Drupal 9 Drupal Express provided by Institute Communications, you should wait until they release a new version of the Georgia Tech theme package before trying to upgrade to Drupal 10.

A list of things to be watchful for when upgrading to Drupal 10 (to be expanded in the near future):

Whitelisting Tags in Module Output

Here's how to whitelist HTML tags in your module output that are normally stripped out by the XSS filter:

    $tagList = array('input');
  
    return array(
      '#markup' => $buffer,
      '#allowed_tags' => array_merge(\Drupal\Component\Utility\Xss::getAdminTagList(), $tagList),
    );

And here's how to allow data URLs in your module output for displaying images with data that you've already pulled in from a data source (code updated 2017-12-11 to a better format that avoids whitescreening in certain use cases):

MySQL Restrictions in Drupal 8 and Later

Drupal 7 began forcing mySQL to act like a traditional SQL server so that all SQL code used in Drupal will be highly compatible with other database systems like PostgreSQL or SQLite. This means that mySQL statements that syntactically work in other contexts may produce errors under Drupal 7 or 9. Drupal 8+ adds the 'ONLY_FULL_GROUP_BY' restriction, which can potentially cause custom mySQL code that worked in Drupal 7 to fail with errors in Drupal 8+.

Here's the exact settings being used in Drupal 8: