>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3459513. --> Reported by: [jurgenhaas](https://www.drupal.org/user/168924) >>> <h3 id="summary-problem-motivation">Problem/Motivation</h3> <p>Now that the book module is extracted from Drupal core (10.3 and later), this module needs to explicitly require the book module.</p> <p>There is an issue with that prior to 10.3 but we can't prevent that from happening since composer already downloads the contrib module, even if not required.</p> <p>For further details, see <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-7"><a href="https://www.drupal.org/project/book/issues/3456958" title="Status: Closed (fixed)">#3456958: BookOutline" plugin does not exist</a></span></p> > Related issue: [Issue #3456958](https://www.drupal.org/node/3456958)