diff --git a/core/modules/media/js/plugins/drupalmedia/plugin.es6.js b/core/modules/media/js/plugins/drupalmedia/plugin.es6.js
index a0f398a022..15b3f5f4d2 100644
--- a/core/modules/media/js/plugins/drupalmedia/plugin.es6.js
+++ b/core/modules/media/js/plugins/drupalmedia/plugin.es6.js
@@ -152,7 +152,10 @@
               }
             });
           }
-          const hostEntityLangcode = document.getElementById(editor.name).getAttribute('data-media-embed-host-entity-langcode');
+          // @see media_field_widget_form_alter().
+          const hostEntityLangcode = document
+            .getElementById(editor.name)
+            .getAttribute('data-media-embed-host-entity-langcode');
           if (hostEntityLangcode) {
             data.langcode = hostEntityLangcode;
           }
diff --git a/core/modules/media/js/plugins/drupalmedia/plugin.js b/core/modules/media/js/plugins/drupalmedia/plugin.js
index e625736448..73092be269 100644
--- a/core/modules/media/js/plugins/drupalmedia/plugin.js
+++ b/core/modules/media/js/plugins/drupalmedia/plugin.js
@@ -120,6 +120,7 @@
               }
             });
           }
+
           var hostEntityLangcode = document.getElementById(editor.name).getAttribute('data-media-embed-host-entity-langcode');
           if (hostEntityLangcode) {
             data.langcode = hostEntityLangcode;
@@ -289,4 +290,4 @@
       linkCommandIntegrator(editor);
     }
   });
-})(jQuery, Drupal, CKEDITOR);
+})(jQuery, Drupal, CKEDITOR);
\ No newline at end of file
diff --git a/core/modules/media/media.module b/core/modules/media/media.module
index 138b246e39..d9e51a24db 100644
--- a/core/modules/media/media.module
+++ b/core/modules/media/media.module
@@ -18,7 +18,6 @@
 use Drupal\field\FieldConfigInterface;
 use Drupal\media\Plugin\media\Source\OEmbedInterface;
 use Drupal\Core\Field\FieldItemListInterface;
-use Drupal\Core\Entity\ContentEntityInterface;
 
 /**
  * Implements hook_help().
@@ -510,12 +509,8 @@ function media_field_widget_form_alter(&$element, FormStateInterface $form_state
     if (!empty($context['items']) && $context['items'] instanceof FieldItemListInterface) {
       $element['#attributes']['data-media-embed-host-entity-langcode'] = $context['items']->getLangcode();
     }
-    else {
-      $entity = $form_state->getFormObject()->getEntity();
-      if ($entity instanceof ContentEntityInterface) {
-        $element['#attributes']['data-media-embed-host-entity-langcode'] = $entity->language()->getId();
-      }
+    elseif ($entity = $form_state->getFormObject()->getEntity()) {
+      $element['#attributes']['data-media-embed-host-entity-langcode'] = $entity->language()->getId();
     }
   }
 }
-
diff --git a/core/modules/media/src/Form/EditorMediaDialog.php b/core/modules/media/src/Form/EditorMediaDialog.php
index 266f2c401e..2f73f9d2e0 100644
--- a/core/modules/media/src/Form/EditorMediaDialog.php
+++ b/core/modules/media/src/Form/EditorMediaDialog.php
@@ -103,10 +103,8 @@ public function buildForm(array $form, FormStateInterface $form_state, EditorInt
 
     $media = $this->entityRepository->loadEntityByUuid('media', $media_embed_element['data-entity-uuid']);
 
-    if (!empty($editor_object['langcode'])) {
-      if ($media->hasTranslation($editor_object['langcode'])) {
-        $media = $media->getTranslation($editor_object['langcode']);
-      }
+    if (!empty($editor_object['langcode']) && $media->hasTranslation($editor_object['langcode'])) {
+      $media = $media->getTranslation($editor_object['langcode']);
     }
     if ($image_field = $this->getMediaImageSourceField($media)) {
       $settings = $media->{$image_field}->getItemDefinition()->getSettings();
@@ -151,18 +149,14 @@ public function buildForm(array $form, FormStateInterface $form_state, EditorInt
       '#access' => $filter_caption->status && ($filter_html->status === FALSE || !empty($allowed_attributes['data-caption'])),
     ];
 
-    if ($form['alt']['#access'] === FALSE && $form['align']['#access'] === FALSE && $form['caption']['#access'] === FALSE) {
+    if ((empty($form['alt']) || $form['alt']['#access'] === FALSE) && $form['align']['#access'] === FALSE && $form['caption']['#access'] === FALSE) {
       $format = $editor->getFilterFormat();
       $form['no_access_notice'] = [
         '#markup' => $this->t('There is nothing to override for this media.'),
       ];
       if ($this->currentUser()->hasPermission('administer filters')) {
-        $text_format_edit_link = $format
-          ->toLink($format->label(), 'edit-form')
-          ->toString();
-        $form['no_access_notice'] = [
-          '#markup' => $this->t('There is nothing to override for this media. Edit the text format %format to modify the attributes that can be overridden.', ['%format' => $text_format_edit_link]),
-        ];
+        $edit_url = $format->toUrl('edit-form')->toString();
+        $form['no_access_notice']['#markup'] = $this->t('There is nothing to override for this media. <a href="@edit_url">Edit the text format %format</a> to modify the attributes that can be overridden.', ['@edit_url' => $edit_url, '%format' => $format->label()]);
       }
     }
 
@@ -195,10 +189,10 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
       $form_state->setValue(['attributes', 'alt'], '""');
     }
 
-    // The `alt` and `title` attributes are optional: if they're not set, their
-    // default values simply will not be overridden. It's important to set
-    // these to FALSE instead of unsetting the value so that We explicitly
-    // inform the client side about the new value.
+    // The `alt` attribute is optional: if it isn't set, the default value
+    // simply will not be overridden. It's important to set it to FALSE
+    // instead of unsetting the value.  This way we explicitly inform
+    // the client side about the new value.
     if ($form_state->hasValue(['attributes', 'alt']) && trim($form_state->getValue(['attributes', 'alt'])) === '') {
       $form_state->setValue(['attributes', 'alt'], FALSE);
     }
diff --git a/core/modules/media/src/Plugin/Filter/MediaEmbed.php b/core/modules/media/src/Plugin/Filter/MediaEmbed.php
index f035425bdb..f07ba49dcd 100644
--- a/core/modules/media/src/Plugin/Filter/MediaEmbed.php
+++ b/core/modules/media/src/Plugin/Filter/MediaEmbed.php
@@ -26,7 +26,7 @@
  * @Filter(
  *   id = "media_embed",
  *   title = @Translation("Embed media"),
- *   description = @Translation("Embeds media items using a custom tag, <code>&lt;drupal-media&gt;</code>. If used in conjunction with the 'Align/Caption' filters, make sure this filter is configured to run after them. If you are using the HTML filter, be sure the <code>data-align</code> and/or <code>data-caption</code> attributes are allowed on the <code>&lt;drupal-media&gt;</code> tag.  If you would like users to be able to override the alt text on image media, add the <code>alt</code> attribute as well to the <code>&lt;drupal-media&gt;</code> tag."),
+ *   description = @Translation("Embeds media items using a custom tag, <code>&lt;drupal-media&gt;</code>. If used in conjunction with the 'Align/Caption' filters, make sure this filter is configured to run after them. If you are using the HTML filter, be sure the <code>data-align</code> and/or <code>data-caption</code> attributes are allowed on the <code>&lt;drupal-media&gt;</code> tag.  If you would like users to be able to override the alt text on image media, add the <code>alt</code> attribute to the <code>&lt;drupal-media&gt;</code> tag  as well."),
  *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_REVERSIBLE,
  *   settings = {
  *     "default_view_mode" = "full",
diff --git a/core/modules/media/tests/src/FunctionalJavascript/CKEditorIntegrationTest.php b/core/modules/media/tests/src/FunctionalJavascript/CKEditorIntegrationTest.php
index a4371b8585..07130ab496 100644
--- a/core/modules/media/tests/src/FunctionalJavascript/CKEditorIntegrationTest.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/CKEditorIntegrationTest.php
@@ -505,8 +505,8 @@ public function testDialogAccess() {
     $page->pressButton('Close');
     $this->getSession()->switchToIFrame('ckeditor');
 
-    // Test that setting disabling `filter_caption` and `filter_align` disables
-    // the respective fields in the dialog.
+    // Test that disabling `filter_caption` and `filter_align` disables the
+    // respective fields in the dialog.
     $filter_format
       ->setFilterConfig('filter_caption', [
         'status' => FALSE,
@@ -537,6 +537,7 @@ public function testDialogAccess() {
     $this->waitForMetadataDialog();
     $assert_session->fieldExists('attributes[data-align]');
     $assert_session->fieldExists('hasCaption');
+    $assert_session->pageTextNotContains('There is nothing to override for this media. Edit the text format Test format to modify the attributes that can be overridden.');
     // The alt field should be unaffected.
     $assert_session->fieldExists('attributes[alt]');
   }
@@ -556,10 +557,10 @@ public function testAlt() {
     $this->assertNotEmpty($assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "default alt")]'));
     $page->pressButton('Edit media');
     $this->waitForMetadataDialog();
-    $alt = $page->findField('attributes[alt]');
+
     // Assert that the placeholder is set to the value of the media field's
     // alt text.
-    $this->assertSame('default alt', $alt->getAttribute('placeholder'));
+    $assert_session->elementAttributeContains('named', ['field', 'attributes[alt]'], 'placeholder', 'default alt');
 
     // Fill in the alt field in the dialog.
     $who_is_zartan = 'Zartan is the leader of the Dreadnoks.';
@@ -569,7 +570,7 @@ public function testAlt() {
 
     // Assert that the img within the media embed within the ckeditor contains
     // the overridden alt text set in the dialog.
-    $this->assertNotEmpty($img = $assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $who_is_zartan . '")]'));
+    $this->assertNotEmpty($assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $who_is_zartan . '")]'));
 
     // Reopen the dialog.
     $page->pressButton('Edit media');
@@ -582,23 +583,26 @@ public function testAlt() {
     // the second time around.
     $cobra_commander_bio = 'The supreme leader of the terrorist organization Cobra';
     // Set the alt field to the new alt text.
-    $alt->setValue($cobra_commander_bio);
+    $page->fillField('attributes[alt]', $cobra_commander_bio);
     $this->submitDialog();
     $this->getSession()->switchToIFrame('ckeditor');
-    // Assert that the img within the media embed within the ckeditor contains
-    // the overridden alt text set in the dialog.
-    $this->assertNotEmpty($img = $assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $cobra_commander_bio . '")]'));
+    // Assert that the img within the media embed preview
+    // within the ckeditor contains the overridden alt text set in the dialog.
+    $this->assertNotEmpty($assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $cobra_commander_bio . '")]'));
 
     // Reopen the dialog.
     $page->pressButton('Edit media');
     $this->waitForMetadataDialog();
-    // The alt field should now display the override instead of the default.
+    // The default value of the alt field should now display the override
+    // instead of the value on the media image field.
     $alt = $page->findField('attributes[alt]');
     $this->assertSame($cobra_commander_bio, $alt->getValue());
 
     // Test that setting alt value to two double quotes will signal to the
     // MediaEmbed filter to unset the attribute on the media image field.
-    $alt->setValue('""');
+    // Note: intentionally adding a space after the two double quotes to test
+    // the string is trimmed to two quotes.
+    $alt->setValue('"" ');
     $this->submitDialog();
     $this->getSession()->switchToIFrame('ckeditor');
     $img = $assert_session->waitForElementVisible('xpath', '//img');
@@ -626,7 +630,7 @@ public function testAlt() {
    */
   public function testTranslationAlt() {
     \Drupal::service('module_installer')->install(['language', 'content_translation']);
-    $this->rebuildContainer();
+    $this->resetAll();
     ConfigurableLanguage::create(['id' => 'fr'])->save();
     ContentLanguageSettings::loadByEntityTypeBundle('media', 'image')
       ->setDefaultLangcode('en')
@@ -674,7 +678,6 @@ public function testTranslationAlt() {
     $translation->title = 'Animaux avec des noms étranges';
     $translation->body->value = $host->body->value;
     $translation->body->format = $host->body->format;
-    $translation->body->lang = 'fr';
     $translation->save();
 
     $this->grantPermissions(Role::load(RoleInterface::AUTHENTICATED_ID), ['translate any entity']);
@@ -690,10 +693,10 @@ public function testTranslationAlt() {
     $this->assertNotEmpty($assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "texte alternatif par défaut")]'));
     $page->pressButton('Edit media');
     $this->waitForMetadataDialog();
-    $alt = $page->findField('attributes[alt]');
+    $alt = $assert_session->fieldExists('attributes[alt]')->getValue();
     // Assert that the placeholder is set to the value of the media field's
     // alt text.
-    $this->assertSame('texte alternatif par défaut', $alt->getAttribute('placeholder'));
+    $assert_session->elementAttributeContains('named', ['field', 'attributes[alt]'], 'placeholder', 'texte alternatif par défaut');
 
     // Fill in the alt field in the dialog.
     $qui_est_zartan = 'Zartan est le chef des Dreadnoks.';
@@ -703,7 +706,7 @@ public function testTranslationAlt() {
 
     // Assert that the img within the media embed within the ckeditor contains
     // the overridden alt text set in the dialog.
-    $this->assertNotEmpty($img = $assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $qui_est_zartan . '")]'));
+    $this->assertNotEmpty($assert_session->waitForElementVisible('xpath', '//img[contains(@alt, "' . $qui_est_zartan . '")]'));
     $this->getSession()->switchToIFrame();
     $page->pressButton('Save');
     $assert_session->elementExists('xpath', '//img[contains(@alt, "' . $qui_est_zartan . '")]');
@@ -982,15 +985,14 @@ public function testAlignment() {
     foreach ($alignments as $alignment) {
       $this->fillFieldInMetadataDialog('attributes[data-align]', $alignment);
       // Now verify the result.
-      $this->assertNotEmpty($assert_session->waitForElementVisible('css', 'drupal-media[data-align="' . $alignment . '"]', 2000));
-      $this->assertNotEmpty($assert_session->waitForElementVisible('css', '.caption-drupal-media.align-' . $alignment, 2000));
-
+      $selector = sprintf('drupal-media[data-align="%s"] .caption-drupal-media.align-%s', $alignment, $alignment);
+      $this->assertNotEmpty($assert_session->waitForElementVisible('css', $selector, 2000));
       // Assert that the resultant downcast drupal-media tag has the proper
       // `data-align` attribute.
-      $drupal_media = $this->getDrupalMediaFromSource();
+      $this->assertNotEmpty($drupal_media = $this->getDrupalMediaFromSource());
       $this->assertSame($alignment, $drupal_media->getAttribute('data-align'));
 
-      // Leave source mode.
+      // Press the source button again to leave source mode.
       $this->pressEditorButton('source');
       // Having entered source mode means we need to reassign an id to the
       // CKEditor iframe.
@@ -1007,7 +1009,7 @@ public function testAlignment() {
     $assert_session->elementExists('css', '.cke_widget_drupalmedia:not([class*="align-"])');
     // Assert that the resultant downcast drupal-media tag has no data-align
     // attribute.
-    $drupal_media = $this->getDrupalMediaFromSource();
+    $this->assertNotEmpty($drupal_media = $this->getDrupalMediaFromSource());
     $this->assertFalse($drupal_media->hasAttribute('data-align'));
   }
 
@@ -1195,8 +1197,8 @@ protected function clickPathLinkByTitleAttribute($text) {
   /**
    * Get the drupal-media element from the ckeditor source.
    *
-   * @return \DOMNode
-   *   The drupal-media element.
+   * @return \DOMNode|null
+   *   The drupal-media element or NULL if it can't be found.
    */
   protected function getDrupalMediaFromSource() {
     $this->pressEditorButton('source');
@@ -1205,7 +1207,13 @@ protected function getDrupalMediaFromSource() {
       ->getValue();
     $dom = Html::load($value);
     $xpath = new \DOMXPath($dom);
-    return $xpath->query('//drupal-media')[0];
+    $list = $xpath->query('//drupal-media');
+    if (!empty($list[0])) {
+      $drupal_media = $list[0];
+      $this->assertInstanceOf(\DOMNode::class, $drupal_media);
+      return $drupal_media;
+    }
+    return NULL;
   }
 
 }