diff --git a/core/lib/Drupal/Core/Entity/ContentEntityConfirmFormBase.php b/core/lib/Drupal/Core/Entity/ContentEntityConfirmFormBase.php
index 887fcae..3583ad4 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityConfirmFormBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityConfirmFormBase.php
@@ -86,9 +86,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
       'submit' => array(
         '#type' => 'submit',
         '#value' => $this->getConfirmText(),
-        '#validate' => array(
-          array($this, 'validate'),
-        ),
         '#submit' => array(
           array($this, 'submitForm'),
         ),
@@ -121,7 +118,7 @@ public function delete(array $form, FormStateInterface $form_state) {}
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, FormStateInterface $form_state) {
+  public function validateForm(array &$form, FormStateInterface $form_state) {
     // Override the default validation implementation as it is not necessary
     // nor possible to validate an entity in a confirmation form.
   }
diff --git a/core/lib/Drupal/Core/Entity/ContentEntityForm.php b/core/lib/Drupal/Core/Entity/ContentEntityForm.php
index 3740600..bcbcc31 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityForm.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityForm.php
@@ -73,15 +73,14 @@ public function form(array $form, FormStateInterface $form_state) {
    * requests.
    * For more information about entity validation, see
    * https://www.drupal.org/node/2015613.
+   *
+   * @return \Drupal\Core\Entity\ContentEntityTypeInterface
+   *   The built entity.
    */
-  public function validate(array $form, FormStateInterface $form_state) {
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    parent::validateForm($form, $form_state);
     $entity = $this->buildEntity($form, $form_state);
     $this->getFormDisplay($form_state)->validateFormValues($entity, $form, $form_state);
-
-    // @todo Remove this.
-    // Execute legacy global validation handlers.
-    $form_state->setValidateHandlers([]);
-    \Drupal::service('form_validator')->executeValidateHandlers($form, $form_state);
     return $entity;
   }
 
diff --git a/core/lib/Drupal/Core/Entity/EntityConfirmFormBase.php b/core/lib/Drupal/Core/Entity/EntityConfirmFormBase.php
index a11e27f..7b320e1 100644
--- a/core/lib/Drupal/Core/Entity/EntityConfirmFormBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityConfirmFormBase.php
@@ -81,9 +81,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
       'submit' => array(
         '#type' => 'submit',
         '#value' => $this->getConfirmText(),
-        '#validate' => array(
-          array($this, 'validate'),
-        ),
         '#submit' => array(
           array($this, 'submitForm'),
         ),
diff --git a/core/lib/Drupal/Core/Entity/EntityForm.php b/core/lib/Drupal/Core/Entity/EntityForm.php
index fb015c7..848937e 100644
--- a/core/lib/Drupal/Core/Entity/EntityForm.php
+++ b/core/lib/Drupal/Core/Entity/EntityForm.php
@@ -219,7 +219,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
     $actions['submit'] = array(
       '#type' => 'submit',
       '#value' => $this->t('Save'),
-      '#validate' => array('::validate'),
       '#submit' => array('::submitForm', '::save'),
     );
 
@@ -246,16 +245,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
 
   /**
    * {@inheritdoc}
-   */
-  public function validate(array $form, FormStateInterface $form_state) {
-    // @todo Remove this.
-    // Execute legacy global validation handlers.
-    $form_state->setValidateHandlers([]);
-    \Drupal::service('form_validator')->executeValidateHandlers($form, $form_state);
-  }
-
-  /**
-   * {@inheritdoc}
    *
    * This is the default entity object builder function. It is called before any
    * other submit handler to build the new entity object to be used by the
diff --git a/core/lib/Drupal/Core/Entity/EntityFormInterface.php b/core/lib/Drupal/Core/Entity/EntityFormInterface.php
index 29b248b..fcf3a93 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormInterface.php
@@ -95,19 +95,6 @@ public function getEntityFromRouteMatch(RouteMatchInterface $route_match, $entit
   public function buildEntity(array $form, FormStateInterface $form_state);
 
   /**
-   * Validates the submitted form values of the entity form.
-   *
-   * @param array $form
-   *   A nested array form elements comprising the form.
-   * @param \Drupal\Core\Form\FormStateInterface $form_state
-   *   The current state of the form.
-   *
-   * @return \Drupal\Core\Entity\ContentEntityTypeInterface
-   *   The built entity.
-   */
-  public function validate(array $form, FormStateInterface $form_state);
-
-  /**
    * Form submission handler for the 'save' action.
    *
    * Normally this method should be overridden to provide specific messages to
diff --git a/core/modules/comment/src/CommentForm.php b/core/modules/comment/src/CommentForm.php
index 10c2152..f6755ce 100644
--- a/core/modules/comment/src/CommentForm.php
+++ b/core/modules/comment/src/CommentForm.php
@@ -257,7 +257,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
       '#type' => 'submit',
       '#value' => $this->t('Preview'),
       '#access' => $preview_mode != DRUPAL_DISABLED,
-      '#validate' => array('::validate'),
       '#submit' => array('::submitForm', '::preview'),
     );
 
@@ -314,8 +313,8 @@ public function buildEntity(array $form, FormStateInterface $form_state) {
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, FormStateInterface $form_state) {
-    $comment = parent::validate($form, $form_state);
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    $comment = parent::validateForm($form, $form_state);
 
     // Customly trigger validation of manually added fields and add in
     // violations.
diff --git a/core/modules/contact/src/MessageForm.php b/core/modules/contact/src/MessageForm.php
index 78de6dd..d77e3d3 100644
--- a/core/modules/contact/src/MessageForm.php
+++ b/core/modules/contact/src/MessageForm.php
@@ -169,7 +169,6 @@ public function actions(array $form, FormStateInterface $form_state) {
     $elements['submit']['#value'] = $this->t('Send message');
     $elements['preview'] = array(
       '#value' => $this->t('Preview'),
-      '#validate' => array('::validate'),
       '#submit' => array('::submitForm', '::preview'),
     );
     return $elements;
@@ -187,10 +186,8 @@ public function preview(array $form, FormStateInterface $form_state) {
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, FormStateInterface $form_state) {
-    parent::validate($form, $form_state);
-
-    $message = $this->entity;
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    $message = parent::validateForm($form, $form_state);
 
     // Check if flood control has been activated for sending emails.
     if (!$this->currentUser()->hasPermission('administer contact forms') && (!$message->isPersonal() || !$this->currentUser()->hasPermission('administer users'))) {
@@ -204,6 +201,8 @@ public function validate(array $form, FormStateInterface $form_state) {
         )));
       }
     }
+
+    return $message;
   }
 
   /**
diff --git a/core/modules/content_translation/src/ContentTranslationHandler.php b/core/modules/content_translation/src/ContentTranslationHandler.php
index 0bd26f4..4bd82d5 100644
--- a/core/modules/content_translation/src/ContentTranslationHandler.php
+++ b/core/modules/content_translation/src/ContentTranslationHandler.php
@@ -428,9 +428,7 @@ public function entityFormAlter(array &$form, FormStateInterface $form_state, En
     $form['#entity_builders'][] = array($this, 'entityFormEntityBuild');
 
     // Handle entity validation.
-    if (isset($form['actions']['submit'])) {
-      $form['actions']['submit']['#validate'][] = array($this, 'entityFormValidate');
-    }
+    $form['#validate'][] = array($this, 'entityFormValidate');
 
     // Handle entity deletion.
     if (isset($form['actions']['delete'])) {
diff --git a/core/modules/menu_ui/menu_ui.module b/core/modules/menu_ui/menu_ui.module
index 95c9e3e..f96536e 100644
--- a/core/modules/menu_ui/menu_ui.module
+++ b/core/modules/menu_ui/menu_ui.module
@@ -412,7 +412,7 @@ function menu_ui_form_node_type_form_alter(&$form, FormStateInterface $form_stat
     '#attributes' => array('class' => array('menu-title-select')),
   );
 
-  $form['actions']['submit']['#validate'][] = 'menu_ui_form_node_type_form_validate';
+  $form['#validate'][] = 'menu_ui_form_node_type_form_validate';
   $form['#entity_builders'][] = 'menu_ui_form_node_type_form_builder';
 }
 
diff --git a/core/modules/node/src/NodeForm.php b/core/modules/node/src/NodeForm.php
index 44fccbf..48a381f 100644
--- a/core/modules/node/src/NodeForm.php
+++ b/core/modules/node/src/NodeForm.php
@@ -273,7 +273,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
       '#access' => $preview_mode != DRUPAL_DISABLED && ($node->access('create') || $node->access('update')),
       '#value' => t('Preview'),
       '#weight' => 20,
-      '#validate' => array('::validate'),
       '#submit' => array('::submitForm', '::preview'),
     );
 
@@ -286,8 +285,8 @@ protected function actions(array $form, FormStateInterface $form_state) {
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, FormStateInterface $form_state) {
-    $node = parent::validate($form, $form_state);
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    $node = parent::validateForm($form, $form_state);
 
     if ($node->id() && (node_last_changed($node->id(), $this->getFormLangcode($form_state)) > $node->getChangedTime())) {
       $form_state->setErrorByName('changed', $this->t('The content on this page has either been modified by another user, or you have already submitted modifications using this form. As a result, your changes cannot be saved.'));