diff --git a/core/modules/book/src/Plugin/Validation/Constraint/BookOutlineConstraintValidator.php b/core/modules/book/src/Plugin/Validation/Constraint/BookOutlineConstraintValidator.php
index dbf2417..1b9f042 100644
--- a/core/modules/book/src/Plugin/Validation/Constraint/BookOutlineConstraintValidator.php
+++ b/core/modules/book/src/Plugin/Validation/Constraint/BookOutlineConstraintValidator.php
@@ -45,7 +45,14 @@ public static function create(ContainerInterface $container) {
   public function validate($entity, Constraint $constraint) {
     if (isset($entity) && !$entity->isNew() && !$entity->isDefaultRevision()) {
       /** @var \Drupal\Core\Entity\ContentEntityInterface $original */
-      $original = $this->bookManager->loadBookLink($entity->id(), FALSE);
+      $original = $this->bookManager->loadBookLink($entity->id(), FALSE) ?: [
+        'bid' => 0,
+        'weight' => 0,
+      ];
+      if (empty($original['pid'])) {
+        $original['pid'] = -1;
+      }
+
       if ($entity->book['bid'] != $original['bid']) {
         $this->context->buildViolation($constraint->message)
           ->atPath('book.bid')
diff --git a/core/modules/book/tests/src/Functional/BookContentModerationTest.php b/core/modules/book/tests/src/Functional/BookContentModerationTest.php
index c42feeb..a6101c4 100644
--- a/core/modules/book/tests/src/Functional/BookContentModerationTest.php
+++ b/core/modules/book/tests/src/Functional/BookContentModerationTest.php
@@ -56,6 +56,11 @@ public function testBookWithForwardRevisions() {
     $this->checkBookNode($book_1, [$book_1_nodes[0], $book_1_nodes[3], $book_1_nodes[4]], FALSE, FALSE, $book_1_nodes[0], []);
     $this->checkBookNode($book_1_nodes[0], [$book_1_nodes[1], $book_1_nodes[2]], $book_1, $book_1, $book_1_nodes[1], [$book_1]);
 
+    // Create a book draft with no changes, then publish it.
+    $this->drupalPostForm('node/' . $book_1->id() . '/edit', [], t('Save and Create New Draft'));
+    $this->assertSession()->pageTextNotContains('You can only change the book outline for the published version of this content.');
+    $this->drupalPostForm('node/' . $book_1->id() . '/edit', [], t('Save and Publish'));
+
     // Try to move Node 2 to a different parent.
     $edit['book[pid]'] = $book_1_nodes[3]->id();
     $this->drupalPostForm('node/' . $book_1_nodes[1]->id() . '/edit', $edit, t('Save and Create New Draft'));