diff --git a/core/modules/editor/editor.module b/core/modules/editor/editor.module
index e9f1a88e65d..77c1f534acd 100644
--- a/core/modules/editor/editor.module
+++ b/core/modules/editor/editor.module
@@ -125,8 +125,9 @@ function editor_form_filter_format_form_alter(&$form, FormStateInterface $form_s
     '#type' => 'select',
     '#title' => t('Text editor'),
     '#options' => $editor_options,
+    '#empty_value' => '_none',
     '#empty_option' => t('None'),
-    '#default_value' => $editor ? $editor->getEditor() : '',
+    '#default_value' => $editor ? $editor->getEditor() : '_none',
     '#ajax' => [
       'trigger_as' => ['name' => 'editor_configure'],
       'callback' => 'editor_form_filter_admin_form_ajax',
@@ -185,14 +186,20 @@ function editor_form_filter_format_form_alter(&$form, FormStateInterface $form_s
  * Button submit handler for filter_format_form()'s 'editor_configure' button.
  */
 function editor_form_filter_admin_format_editor_configure($form, FormStateInterface $form_state) {
+  $format = $form_state->getFormObject()->getEntity();
   $editor = $form_state->get('editor');
+
+  if (!$editor && !$format->isNew()) {
+    $editor = editor_load($format->id());
+    $form_state->set('editor', $editor);
+  }
+
   $editor_value = $form_state->getValue(['editor', 'editor']);
   if ($editor_value !== NULL) {
-    if ($editor_value === '') {
+    if ($editor_value === '_none') {
       $form_state->set('editor', FALSE);
     }
     elseif (empty($editor) || $editor_value !== $editor->getEditor()) {
-      $format = $form_state->getFormObject()->getEntity();
       $editor = Editor::create([
         'format' => $format->isNew() ? NULL : $format->id(),
         'editor' => $editor_value,
@@ -223,7 +230,7 @@ function editor_form_filter_admin_format_validate($form, FormStateInterface $for
   // 'Configure' button won't be clicked automatically. So, when the user has
   // selected a text editor and has then clicked 'Save configuration', we should
   // point out that the user must still configure the text editor.
-  if ($form_state->getValue(['editor', 'editor']) !== '' && !$form_state->get('editor')) {
+  if ($form_state->getValue(['editor', 'editor']) !== '_none' && !$form_state->get('editor')) {
     $form_state->setErrorByName('editor][editor', t('You must configure the selected text editor.'));
   }
 }
diff --git a/core/modules/editor/src/Tests/EditorAdminTest.php b/core/modules/editor/src/Tests/EditorAdminTest.php
index 4315a6dabd8..edf2b52c686 100644
--- a/core/modules/editor/src/Tests/EditorAdminTest.php
+++ b/core/modules/editor/src/Tests/EditorAdminTest.php
@@ -84,7 +84,7 @@ class EditorAdminTest extends WebTestBase {
 
     // Switch back to 'None' and check the Unicorn Editor's settings are gone.
     $edit = [
-      'editor[editor]' => '',
+      'editor[editor]' => '_none',
     ];
     $this->drupalPostAjaxForm(NULL, $edit, 'editor_configure');
     $unicorn_setting = $this->xpath('//input[@name="editor[settings][ponies_too]" and @type="checkbox" and @checked]');
diff --git a/core/modules/editor/tests/src/FunctionalJavascript/EditorFilterFormConfigurationTest.php b/core/modules/editor/tests/src/FunctionalJavascript/EditorFilterFormConfigurationTest.php
new file mode 100644
index 00000000000..074064db803
--- /dev/null
+++ b/core/modules/editor/tests/src/FunctionalJavascript/EditorFilterFormConfigurationTest.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Drupal\Tests\editor\FunctionalJavascript;
+
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+
+/**
+ * Tests Text Editor's integration with the Text Format configuration form.
+ *
+ * @group editor
+ */
+class EditorFilterFormConfigurationTest extends JavascriptTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['ckeditor'];
+
+  /**
+   * Tests switching between editors.
+   */
+  public function testSwitchingEditors() {
+    $assert_session = $this->assertSession();
+    $page = $this->getSession()->getPage();
+
+    $this->drupalLogin($this->createUser(['administer filters']));
+
+    // Configure a format to use CKEditor.
+    $this->drupalGet('admin/config/content/formats');
+    $assert_session->pageTextNotContains('CKEditor');
+    $this->clickLink('Configure');
+
+    $page->selectFieldOption('editor[editor]', 'ckeditor');
+    $assert_session->assertWaitOnAjaxRequest();
+    $assert_session->elementExists('css', '#ckeditor-button-configuration');
+
+    $page->pressButton('Save configuration');
+    $assert_session->pageTextContains('The text format Plain text has been updated.');
+    $assert_session->pageTextContains('CKEditor');
+
+    // Switch between no editor and CKEditor to ensure the originally configured
+    // editor is not lost.
+    $this->clickLink('Configure');
+    $assert_session->elementExists('css', '#ckeditor-button-configuration');
+
+    $page->selectFieldOption('editor[editor]', '_none');
+    $assert_session->assertWaitOnAjaxRequest();
+    $this->htmlOutput($page->getContent());
+    $assert_session->elementNotExists('css', '#ckeditor-button-configuration');
+
+    $page->selectFieldOption('editor[editor]', 'ckeditor');
+    $assert_session->assertWaitOnAjaxRequest();
+    $assert_session->elementExists('css', '#ckeditor-button-configuration');
+
+    $page->pressButton('Save configuration');
+    $assert_session->pageTextContains('The text format Plain text has been updated.');
+    $assert_session->pageTextContains('CKEditor');
+  }
+
+}