diff -u b/core/lib/Drupal/Core/Block/BlockBase.php b/core/lib/Drupal/Core/Block/BlockBase.php
--- b/core/lib/Drupal/Core/Block/BlockBase.php
+++ b/core/lib/Drupal/Core/Block/BlockBase.php
@@ -10,8 +10,8 @@
 use Drupal\Component\Utility\Unicode;
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Language\LanguageInterface;
-use Drupal\Core\Plugin\PluginFormInterface;
 use Drupal\Core\Plugin\PluginWithFormsInterface;
+use Drupal\Core\Plugin\PluginWithFormsTrait;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Component\Transliteration\TransliterationInterface;
 
@@ -27,6 +27,7 @@
 abstract class BlockBase extends ContextAwarePluginBase implements BlockPluginInterface, PluginWithFormsInterface {
 
   use ContextAwarePluginAssignmentTrait;
+  use PluginWithFormsTrait;
 
   /**
    * The transliteration service.
@@ -275,21 +276,2 @@
 
-  /**
-   * {@inheritdoc}
-   */
-  public function getFormClass($operation) {
-    if (isset($this->getPluginDefinition()['forms'][$operation])) {
-      return $this->getPluginDefinition()['forms'][$operation];
-    }
-    elseif ($operation === 'configure') {
-      return static::class;
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function hasFormClass($operation) {
-    return !empty($this->getFormClass($operation));
-  }
-
 }
diff -u b/core/lib/Drupal/Core/Plugin/PluginWithFormsTrait.php b/core/lib/Drupal/Core/Plugin/PluginWithFormsTrait.php
--- b/core/lib/Drupal/Core/Plugin/PluginWithFormsTrait.php
+++ b/core/lib/Drupal/Core/Plugin/PluginWithFormsTrait.php
@@ -14,7 +14,7 @@
     if (isset($this->getPluginDefinition()['forms'][$operation])) {
       return $this->getPluginDefinition()['forms'][$operation];
     }
-    elseif ($operation === 'configure') {
+    elseif ($operation === 'configure' && $this instanceof PluginFormInterface) {
       return static::class;
     }
   }
diff -u b/core/tests/Drupal/Tests/Core/Plugin/PluginWithFormsTraitTest.php b/core/tests/Drupal/Tests/Core/Plugin/PluginWithFormsTraitTest.php
--- b/core/tests/Drupal/Tests/Core/Plugin/PluginWithFormsTraitTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/PluginWithFormsTraitTest.php
@@ -3,6 +3,8 @@
 namespace Drupal\Tests\Core\Plugin;
 
 use Drupal\Component\Plugin\PluginBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\PluginFormInterface;
 use Drupal\Core\Plugin\PluginWithFormsInterface;
 use Drupal\Core\Plugin\PluginWithFormsTrait;
 use Drupal\Tests\UnitTestCase;
@@ -51,4 +53,15 @@
 
-class TestClass extends PluginBase implements PluginWithFormsInterface {
+class TestClass extends PluginBase implements PluginWithFormsInterface, PluginFormInterface {
   use PluginWithFormsTrait;
+
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    return [];
+  }
+
+  public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
+  }
+
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+  }
+
 }