>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #2945824. --> Reported by: [golddragon007](https://www.drupal.org/user/2723471) Related to !50 >>> <p>What are the steps required to reproduce the bug?</p> <ol> <li>Install a new Drupal 8.4 site and enable book module.</li> <li>Create a book</li> <li>Create 3 pages in this hierarhy: <img src="https://www.drupal.org/files/issues/hierarhy.JPG" alt="Page hierarhy structure"></li> <li>Remove the parent element from the outline (on my image the Page 1)</li> </ol> <p>What behavior were you expecting?<br> I think if you delete a parent, move the child one deph up. So it shoud be look like this:<br> Book<br> - Page 1.1<br> - Page 2</p> <p>What happened instead?<br> Here are the images from the book (root) and the pages:<br> <img src="https://www.drupal.org/files/issues/book_0.JPG" alt="Book"><br> <img src="https://www.drupal.org/files/issues/page-1.JPG" alt="Page 1"><br> <img src="https://www.drupal.org/files/issues/page-2.JPG" alt="Page 2"></p> <p>But the page 1.1:<br> <img src="https://www.drupal.org/files/issues/page-1-1.JPG" alt="Page 1.1"><br> Broken navigation, it's not under the book only from the current page, so deleted parent's child will be lost, and buggy.</p>