The dependency core/jquery.ui is not loading into the theme. jQuery is loaded as it is included by default but jquery.ui refuses to load.

  version: 1.x
    js/popup.js: {}
    - core/jquery
    - core/jquery.ui

  - theme/popup

I have also tried attaching the library using the code below, but still no luck.

// theme.theme
function theme_page_attachments_alter(&$page) {
  $route = \Drupal::routeMatch()->getRouteObject();
  $is_admin = \Drupal::service('router.admin_context')->isAdminRoute($route);
  if(!$is_admin) {
    $page['#attached']['library'][] = 'theme/popup';

I have seen multiple references to core/jquery.ui throughout drupals files. So am a little confused.

I feel like i must be missing something obvious.

jQuery UI will load in fine if you are logged in, but again i believe this is included by default for admin users.

2 Answers 2


For those that are trying to use the built in jquery ui you must include -core/drupal.dialog as a dependency in your theme.libraries.yml for it to work


You made a typo in your theme.libraries.yml, dependancies should be dependencies.

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