diff --git a/core/modules/action/src/ActionFormBase.php b/core/modules/action/src/ActionFormBase.php
index 3fafd035ee..f1cffad7c3 100644
--- a/core/modules/action/src/ActionFormBase.php
+++ b/core/modules/action/src/ActionFormBase.php
@@ -14,18 +14,18 @@
 abstract class ActionFormBase extends EntityForm {
 
   /**
-   * The action plugin being configured.
+   * The action storage.
    *
-   * @var \Drupal\Core\Action\ActionInterface
+   * @var \Drupal\Core\Entity\EntityStorageInterface
    */
-  protected $plugin;
+  protected $storage;
 
   /**
-   * The action storage.
+   * The action entity.
    *
-   * @var \Drupal\Core\Entity\EntityStorageInterface
+   * @var \Drupal\system\ActionConfigEntityInterface
    */
-  protected $storage;
+  protected $entity;
 
   /**
    * Constructs a new action form.
@@ -46,14 +46,6 @@ public static function create(ContainerInterface $container) {
     );
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function buildForm(array $form, FormStateInterface $form_state) {
-    $this->plugin = $this->entity->getPlugin();
-    return parent::buildForm($form, $form_state);
-  }
-
   /**
    * {@inheritdoc}
    */
@@ -85,8 +77,8 @@ public function form(array $form, FormStateInterface $form_state) {
       '#value' => $this->entity->getType(),
     ];
 
-    if ($this->plugin instanceof PluginFormInterface) {
-      $form += $this->plugin->buildConfigurationForm($form, $form_state);
+    if ($plugin = $this->getPlugin()) {
+      $form += $plugin->buildConfigurationForm($form, $form_state);
     }
 
     return parent::form($form, $form_state);
@@ -96,7 +88,7 @@ public function form(array $form, FormStateInterface $form_state) {
    * Determines if the action already exists.
    *
    * @param string $id
-   *   The action ID
+   *   The action ID.
    *
    * @return bool
    *   TRUE if the action exists, FALSE otherwise.
@@ -120,9 +112,8 @@ protected function actions(array $form, FormStateInterface $form_state) {
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
     parent::validateForm($form, $form_state);
-
-    if ($this->plugin instanceof PluginFormInterface) {
-      $this->plugin->validateConfigurationForm($form, $form_state);
+    if ($plugin = $this->getPlugin()) {
+      $plugin->validateConfigurationForm($form, $form_state);
     }
   }
 
@@ -131,9 +122,8 @@ public function validateForm(array &$form, FormStateInterface $form_state) {
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     parent::submitForm($form, $form_state);
-
-    if ($this->plugin instanceof PluginFormInterface) {
-      $this->plugin->submitConfigurationForm($form, $form_state);
+    if ($plugin = $this->getPlugin()) {
+      $plugin->submitConfigurationForm($form, $form_state);
     }
   }
 
@@ -147,4 +137,17 @@ public function save(array $form, FormStateInterface $form_state) {
     $form_state->setRedirect('entity.action.collection');
   }
 
+  /**
+   * Gets the action plugin while ensuring it implements configuration forms.
+   *
+   * @return \Drupal\Core\Action\ActionInterface|\Drupal\Core\Plugin\PluginFormInterface|null
+   *   The action plugin, or NULL if it does not implement configuration forms.
+   */
+  protected function getPlugin() {
+    if ($this->entity->getPlugin() instanceof PluginFormInterface) {
+      return $this->entity->getPlugin();
+    }
+    return NULL;
+  }
+
 }
diff --git a/core/modules/action/tests/action_form_ajax_test/action_form_ajax_test.info.yml b/core/modules/action/tests/action_form_ajax_test/action_form_ajax_test.info.yml
new file mode 100644
index 0000000000..020e9ef45d
--- /dev/null
+++ b/core/modules/action/tests/action_form_ajax_test/action_form_ajax_test.info.yml
@@ -0,0 +1,7 @@
+name: action_form_ajax_test
+type: module
+description: 'module used for testing ajax in action config entity forms.'
+package: Core
+version: VERSION
+core: 8.x
+hidden: true
diff --git a/core/modules/action/tests/action_form_ajax_test/config/schema/action_form_ajax_test.schema.yml b/core/modules/action/tests/action_form_ajax_test/config/schema/action_form_ajax_test.schema.yml
new file mode 100644
index 0000000000..7ebe2e1b6d
--- /dev/null
+++ b/core/modules/action/tests/action_form_ajax_test/config/schema/action_form_ajax_test.schema.yml
@@ -0,0 +1,7 @@
+action.configuration.action_form_ajax_test:
+  type: action_configuration_default
+  label: 'action_form_ajax_test action'
+  mapping:
+    party_time:
+      type: string
+      label: 'The time of the party.'
diff --git a/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php b/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php
new file mode 100644
index 0000000000..bf8bd5b1f3
--- /dev/null
+++ b/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php
@@ -0,0 +1,89 @@
+<?php
+
+namespace Drupal\action_form_ajax_test\Plugin\Action;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Action\ConfigurableActionBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Session\AccountInterface;
+
+/**
+ * Plugin used for testing ajax in action config entity forms.
+ *
+ * @Action(
+ *   id = "action_form_ajax_test",
+ *   label = @Translation("action_form_ajax_test"),
+ *   type = "system"
+ * )
+ */
+class ActionAjaxTest extends ConfigurableActionBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultConfiguration() {
+    return [
+      'party_time' => '',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function access($object, AccountInterface $account = NULL, $return_as_object = FALSE) {
+    $result = AccessResult::allowed();
+    return $return_as_object ? $result : $result->isAllowed();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function execute() {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $having_a_party = $form_state->getValue('having_a_party', !empty($this->configuration['party_time']));
+    $form['having_a_party'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Are we having a party?'),
+      '#ajax' => [
+        'wrapper' => 'party-container',
+        'callback' => [$this, 'partyCallback'],
+      ],
+      '#default_value' => $having_a_party,
+    ];
+    $form['container'] = [
+      '#type' => 'container',
+      '#prefix' => '<div id="party-container">',
+      '#suffix' => '</div>',
+    ];
+
+    if ($having_a_party) {
+      $form['container']['party_time'] = [
+        '#type' => 'textfield',
+        '#title' => $this->t('Party time'),
+        '#default_value' => $this->configuration['party_time'],
+      ];
+    }
+
+    return $form;
+  }
+
+  /**
+   * Callback for party checkbox.
+   */
+  public function partyCallback(array $form, FormStateInterface $form_state) {
+    return $form['container'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    $this->configuration['party_time'] = $form_state->getValue('party_time');
+  }
+
+}
diff --git a/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php b/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php
new file mode 100644
index 0000000000..6b9aa75257
--- /dev/null
+++ b/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Drupal\Tests\action\FunctionalJavascript;
+
+use Drupal\Core\Url;
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+use Drupal\system\Entity\Action;
+
+/**
+ * Tests action plugins using Javascript.
+ *
+ * @group action
+ */
+class ActionFormAjaxTest extends JavascriptTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['action', 'action_form_ajax_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $user = $this->drupalCreateUser(['administer actions']);
+    $this->drupalLogin($user);
+  }
+
+  /**
+   * Tests action plugins with AJAX save their configuration.
+   */
+  public function testActionConfigurationWithAjax() {
+    $url = Url::fromRoute('action.admin_add', ['action_id' => 'action_form_ajax_test']);
+    $this->drupalGet($url);
+    $this->assertSession()->statusCodeEquals(200);
+    $page = $this->getSession()->getPage();
+
+    $id = 'test_plugin';
+    $page->find('css', '[name="id"]')
+      ->setValue($id);
+
+    $page->find('css', '[name="having_a_party"]')
+      ->check();
+    $this->assertSession()->waitForElement('css', '[name="party_time"]');
+
+    $party_time = 'Evening';
+    $page->find('css', '[name="party_time"]')
+      ->setValue($party_time);
+
+    $page->find('css', '[value="Save"]')
+      ->click();
+
+    $url = Url::fromRoute('entity.action.collection');
+    $this->assertSession()->pageTextContains('The action has been successfully saved.');
+    $this->assertSession()->addressEquals($url);
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Check storage.
+    $instance = Action::load($id);
+    $configuration = $instance->getPlugin()->getConfiguration();
+    $this->assertEquals(['party_time' => $party_time], $configuration);
+
+    // Configuration should be shown in edit form.:
+    $this->drupalGet($instance->toUrl('edit-form'));
+    $this->assertSession()->checkboxChecked('having_a_party');
+    $this->assertSession()->fieldValueEquals('party_time', $party_time);
+  }
+
+}