diff --git a/core/lib/Drupal/Core/Field/FieldItemList.php b/core/lib/Drupal/Core/Field/FieldItemList.php
index ae7298e43cf8749d557bd2e3f7dfbbde40c4e37c..4bab6f40ac50a8ee32ad359f9ba1b839517b6d26 100644
--- a/core/lib/Drupal/Core/Field/FieldItemList.php
+++ b/core/lib/Drupal/Core/Field/FieldItemList.php
@@ -322,6 +322,7 @@ public function defaultValuesFormSubmit(array $element, array &$form, FormStateI
       $widget->extractFormValues($this, $element, $form_state);
       return $this->getValue();
     }
+    return [];
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php b/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
index 1d9a19e0e5fc1e02e6a038679ff443cc2229d5e8..1dd4e672113fa9090142898a60a7db76bbf26c8a 100644
--- a/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
+++ b/core/tests/Drupal/Tests/Core/Field/FieldItemListTest.php
@@ -330,7 +330,7 @@ public function testDefaultValuesFormSubmit() {
     $field_list->expects($this->never())
       ->method('getValue');
 
-    $this->assertNull($field_list->defaultValuesFormSubmit([], $form, $form_state));
+    $this->assertArrayEquals([], $field_list->defaultValuesFormSubmit([], $form, $form_state));
   }
 
 }