diff --git a/core/modules/comment/comment.services.yml b/core/modules/comment/comment.services.yml
index 94540d1..8bc91b3 100644
--- a/core/modules/comment/comment.services.yml
+++ b/core/modules/comment/comment.services.yml
@@ -15,4 +15,4 @@ services:
 
   comment.post_render_cache:
     class: Drupal\comment\CommentPostRenderCache
-    arguments: ['@entity.manager', '@entity.form_builder']
+    arguments: ['@entity.manager', '@entity.form_builder', '@current_user']
diff --git a/core/modules/comment/src/CommentForm.php b/core/modules/comment/src/CommentForm.php
index 3b800b3..1580181 100644
--- a/core/modules/comment/src/CommentForm.php
+++ b/core/modules/comment/src/CommentForm.php
@@ -130,6 +130,11 @@ public function form(array $form, array &$form_state) {
       $date = !empty($comment->date) ? $comment->date : DrupalDateTime::createFromTimestamp($comment->getCreatedTime());
     }
 
+    $form['uid'] = array(
+      '#type' => 'value',
+      '#value' => $comment->getOwnerId(),
+    );
+
     // Add the author name field depending on the current user.
     $form['name']['widget'][0]['value']['#required'] = ($this->currentUser->isAnonymous() && $anonymous_contact == COMMENT_ANONYMOUS_MUST_CONTACT);
     if ($is_admin) {
@@ -237,7 +242,6 @@ protected function actions(array $form, array &$form_state) {
    * Overrides Drupal\Core\Entity\EntityForm::validate().
    */
   public function validate(array $form, array &$form_state) {
-    parent::validate($form, $form_state);
     $entity = $this->entity;
 
     if (!$entity->isNew()) {
@@ -265,6 +269,7 @@ public function validate(array $form, array &$form_state) {
         }
       }
     }
+    parent::validate($form, $form_state);
   }
 
   /**
diff --git a/core/modules/comment/src/CommentPostRenderCache.php b/core/modules/comment/src/CommentPostRenderCache.php
index 15831e0..897328c 100644
--- a/core/modules/comment/src/CommentPostRenderCache.php
+++ b/core/modules/comment/src/CommentPostRenderCache.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Entity\EntityFormBuilderInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Session\AccountInterface;
 use Drupal\field\Entity\FieldConfig;
 
 /**
@@ -31,16 +32,26 @@ class CommentPostRenderCache {
   protected $entityFormBuilder;
 
   /**
+   * The current user.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $currentUser;
+
+  /**
    * Constructs a new CommentPostRenderCache object.
    *
    * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
    *   The entity manager service.
    * @param \Drupal\Core\Entity\EntityFormBuilderInterface $entity_form_builder
    *   The entity form builder service.
+   * @param \Drupal\Core\Session\AccountInterface $current_user
+   *   The current user.
    */
-  public function __construct(EntityManagerInterface $entity_manager, EntityFormBuilderInterface $entity_form_builder) {
+  public function __construct(EntityManagerInterface $entity_manager, EntityFormBuilderInterface $entity_form_builder, AccountInterface $current_user) {
     $this->entityManager = $entity_manager;
     $this->entityFormBuilder = $entity_form_builder;
+    $this->currentUser = $current_user;
   }
 
   /**
@@ -67,6 +78,7 @@ public function renderForm(array $element, array $context) {
       'field_name' => $field_name,
       'comment_type' => $field->getSetting('bundle'),
       'pid' => NULL,
+      'uid' => $this->currentUser->id(),
     );
     $comment = $this->entityManager->getStorage('comment')->create($values);
     $form = $this->entityFormBuilder->getForm($comment);
diff --git a/core/modules/comment/src/Controller/CommentController.php b/core/modules/comment/src/Controller/CommentController.php
index e550afc..2e4090b 100644
--- a/core/modules/comment/src/Controller/CommentController.php
+++ b/core/modules/comment/src/Controller/CommentController.php
@@ -256,6 +256,7 @@ public function getReplyForm(Request $request, $entity_type, $entity_id, $field_
       'pid' => $pid,
       'entity_type' => $entity->getEntityTypeId(),
       'field_name' => $field_name,
+      'uid' => $this->currentUser()->id(),
     ));
     $build['comment_form'] = $this->entityFormBuilder()->getForm($comment);
 
diff --git a/core/modules/comment/src/Plugin/Field/FieldFormatter/CommentDefaultFormatter.php b/core/modules/comment/src/Plugin/Field/FieldFormatter/CommentDefaultFormatter.php
index 4597761..2c5740a 100644
--- a/core/modules/comment/src/Plugin/Field/FieldFormatter/CommentDefaultFormatter.php
+++ b/core/modules/comment/src/Plugin/Field/FieldFormatter/CommentDefaultFormatter.php
@@ -192,6 +192,7 @@ public function viewElements(FieldItemListInterface $items) {
               'field_name' => $field_name,
               'comment_type' => $this->getFieldSetting('comment_type'),
               'pid' => NULL,
+              'uid' => $this->currentUser->id(),
             ));
             $output['comment_form'] = $this->entityFormBuilder->getForm($comment);
           }