diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index 3e88997a1cf5e7c7f6662c4e5ece1293a8af4d52..cb7148f4c54449fe9745a28d5c358b8e1f56a42f 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -768,9 +768,6 @@ field.field_settings.entity_reference:
         PluginExists:
           manager: plugin.manager.entity_reference_selection
           interface: 'Drupal\Core\Entity\EntityReferenceSelection\SelectionInterface'
-          # @todo Remove this line and explicitly require valid entity reference
-          # selection plugin IDs in https://drupal.org/i/3420198.
-          allowFallback: true
     handler_settings:
       type: entity_reference_selection.[%parent.handler]
       label: 'Entity reference selection plugin settings'
diff --git a/core/modules/node/tests/src/Kernel/NodeFieldOverridesTest.php b/core/modules/node/tests/src/Kernel/NodeFieldOverridesTest.php
index 70c4538a4a5796f2153deb2a67c25ad00b76e5e4..e8d433dc59a4b27a26da8df1654672118f6869c2 100644
--- a/core/modules/node/tests/src/Kernel/NodeFieldOverridesTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeFieldOverridesTest.php
@@ -34,7 +34,7 @@ class NodeFieldOverridesTest extends EntityKernelTestBase {
    */
   protected function setUp(): void {
     parent::setUp();
-    $this->installConfig(['user']);
+    $this->installConfig(['user', 'field', 'node']);
     $this->user = $this->createUser();
     \Drupal::service('current_user')->setAccount($this->user);
   }
@@ -52,6 +52,7 @@ public function testFieldOverrides(): void {
     }
     $uid_field = \Drupal::service('entity_field.manager')->getBaseFieldDefinitions('node')['uid'];
     $config = $uid_field->getConfig('ponies');
+    $config->setSetting('handler', 'default:user');
     $config->save();
     $this->assertEquals('Drupal\node\Entity\Node::getDefaultEntityOwner', $config->get('default_value_callback'));
     /** @var \Drupal\node\NodeInterface $node */