diff --git a/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php b/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
index 1d8d859588..4d2bf4d600 100644
--- a/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
+++ b/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
@@ -6,6 +6,7 @@
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Test\AssertMailTrait;
@@ -1069,6 +1070,68 @@ public function testNodeFieldTranslation() {
     $this->assertRaw('FR label');
   }
 
+  /**
+   * Test translation of a default value of a text with summary field.
+   */
+  public function testTextWithSummaryDefaultValue() {
+    NodeType::create(['type' => 'article', 'name' => 'Article'])->save();
+
+    $field_name = 'translatable_field';
+    $field_storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'node',
+      'type' => 'text_with_summary',
+    ]);
+
+    $field_storage->setSetting('translatable_storage_setting', 'translatable_storage_setting');
+    $field_storage->save();
+    $field = FieldConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'node',
+      'bundle' => 'article',
+      'default_value' => [[
+        'value' => 'Default text',
+        'summary' => 'Default summary',
+        'format' => 'filtered_html',
+      ]]
+    ]);
+    $field->save();
+
+    $form_display = EntityFormDisplay::create([
+      'targetEntityType' => 'node',
+      'bundle' => 'article',
+      'mode' => 'default',
+      'status' => TRUE,
+    ]);
+    $form_display->setComponent($field_name, ['weight' => 10]);
+    $form_display->save();
+
+    $this->drupalLogin($this->adminUser);
+
+    $this->drupalGet('node/add/article');
+    $this->assertSession()->pageTextContains('Default text');
+    $this->assertSession()->pageTextContains('Default summary');
+
+    $this->drupalGet("entity_test/structure/article/fields/node.article.$field_name/translate");
+    $this->clickLink('Add');
+
+    $form_values = [
+      'translation[config_names][field.field.node.article.translatable_field][default_value][0][value]' => 'FR default text',
+      'translation[config_names][field.field.node.article.translatable_field][default_value][0][summary]' => 'FR default summary',
+    ];
+    $this->drupalPostForm(NULL, $form_values, 'Save translation');
+    $this->assertSession()->pageTextContains('Successfully saved French translation.');
+
+    // Check that the translations are saved.
+    $this->clickLink('Add');
+    $this->assertSession()->pageTextContains('FR default text');
+    $this->assertSession()->pageTextContains('FR default summary');
+    $language = ConfigurableLanguage::load('fr');
+    $this->drupalGet('fr/node/add/article', ['language' => $language]);
+    $this->assertSession()->pageTextContains('FR default text');
+    $this->assertSession()->pageTextContains('FR default summary');
+  }
+
   /**
    * Gets translation from locale storage.
    *