diff --git a/core/modules/path/src/Plugin/Field/FieldType/PathItem.php b/core/modules/path/src/Plugin/Field/FieldType/PathItem.php
index 6976bab..4106381 100644
--- a/core/modules/path/src/Plugin/Field/FieldType/PathItem.php
+++ b/core/modules/path/src/Plugin/Field/FieldType/PathItem.php
@@ -17,7 +17,8 @@
  *   description = @Translation("An entity field containing a path alias and related data."),
  *   no_ui = TRUE,
  *   default_widget = "path",
- *   list_class = "\Drupal\path\Plugin\Field\FieldType\PathFieldItemList"
+ *   list_class = "\Drupal\path\Plugin\Field\FieldType\PathFieldItemList",
+ *   constraints = {"PathAlias" = {}},
  * )
  */
 class PathItem extends FieldItemBase {
@@ -123,19 +124,13 @@ public function postSave($update) {
       }
     }
     else {
-      $entity = $this->getEntity();
-      // Prevent changes to the URL alias if the entity being saved is not the
-      // default revision.
-      if (!$entity->isDefaultRevision() && ($this->pid || $this->alias)) {
-        drupal_set_message($this->t('You cannot change the URL alias until you publish this @entity_type_label.', ['@entity_type_label' => $entity->getEntityType()->getLabel()]), 'error');
-        return;
-      }
       // Delete old alias if user erased it.
       if ($this->pid && !$this->alias) {
         \Drupal::service('path.alias_storage')->delete(['pid' => $this->pid]);
       }
       // Only save a non-empty alias.
       elseif ($this->alias) {
+        $entity = $this->getEntity();
         \Drupal::service('path.alias_storage')->save('/' . $entity->urlInfo()->getInternalPath(), $this->alias, $this->getLangcode(), $this->pid);
       }
     }
diff --git a/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraint.php b/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraint.php
new file mode 100644
index 0000000..d456cc6
--- /dev/null
+++ b/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraint.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Drupal\path\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Validation constraint for changing path aliases in forward revisions.
+ *
+ * @Constraint(
+ *   id = "PathAlias",
+ *   label = @Translation("Path alias.", context = "Validation"),
+ * )
+ */
+class PathAliasConstraint extends Constraint {
+
+  public $message = 'This is not the default revision. You can only change the URL alias for the <em>published</em> version of this content.';
+
+}
diff --git a/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraintValidator.php b/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraintValidator.php
new file mode 100644
index 0000000..986df4b
--- /dev/null
+++ b/core/modules/path/src/Plugin/Validation/Constraint/PathAliasConstraintValidator.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\path\Plugin\Validation\Constraint;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+/**
+ * Constraint validator for changing path aliases in forward revisions.
+ */
+class PathAliasConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  private $entityTypeManager;
+
+  /**
+   * Creates a new PathAliasConstraintValidator instance.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity_type.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($value, Constraint $constraint) {
+    $entity = !empty($value->getParent()) ? $value->getEntity() : NULL;
+
+    if ($entity && !$entity->isNew() && !$entity->isDefaultRevision()) {
+      /** @var \Drupal\Core\Entity\ContentEntityInterface $original */
+      $original = $this->entityTypeManager->getStorage($entity->getEntityTypeId())->loadUnchanged($entity->id());
+      if ($value->alias != $original->path->alias) {
+        $this->context->addViolation($constraint->message);
+      }
+    }
+  }
+
+}
diff --git a/core/modules/path/tests/src/Functional/PathContentModerationTest.php b/core/modules/path/tests/src/Functional/PathContentModerationTest.php
index 51620b2..9fe5627 100644
--- a/core/modules/path/tests/src/Functional/PathContentModerationTest.php
+++ b/core/modules/path/tests/src/Functional/PathContentModerationTest.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\Tests\path\Functional;
 
-use Drupal\Core\Path\AliasStorage;
 use Drupal\node\Entity\NodeType;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\workflows\Entity\Workflow;
@@ -10,6 +9,7 @@
 /**
  * Tests path aliases with Content Moderation.
  *
+ * @group content_moderation
  * @group path
  */
 class PathContentModerationTest extends BrowserTestBase {
@@ -59,7 +59,7 @@ public function testNodePathAlias() {
       'title[0][value]' => 'forward revision',
       'path[0][alias]' => '/moderated-content',
     ], t('Save and Create New Draft'));
-    $this->assertSession()->pageTextContains('You cannot change the URL alias until you publish this Content.');
+    $this->assertSession()->pageTextNotContains('This is not the default revision. You can only change the URL alias for the published version of this content.');
 
     // Create some moderated content with no path alias.
     $this->drupalGet('node/add/moderated');
@@ -77,7 +77,7 @@ public function testNodePathAlias() {
       'title[0][value]' => 'forward revision',
       'path[0][alias]' => '/forward-revision',
     ], t('Save and Create New Draft'));
-    $this->assertSession()->pageTextContains('You cannot change the URL alias until you publish this Content.');
+    $this->assertSession()->pageTextContains('This is not the default revision. You can only change the URL alias for the published version of this content.');
 
     // Create some moderated content with no path alias.
     $this->drupalGet('node/add/moderated');
@@ -95,7 +95,7 @@ public function testNodePathAlias() {
       'title[0][value]' => 'forward revision',
       'path[0][alias]' => '',
     ], t('Save and Create New Draft'));
-    $this->assertSession()->pageTextNotContains('You cannot change the URL alias until you publish this Content.');
-
+    $this->assertSession()->pageTextNotContains('This is not the default revision. You can only change the URL alias for the published version of this content.');
   }
+
 }