diff --git a/core/modules/media/src/Entity/Media.php b/core/modules/media/src/Entity/Media.php
index f9c06093ac..b17f7c5edf 100644
--- a/core/modules/media/src/Entity/Media.php
+++ b/core/modules/media/src/Entity/Media.php
@@ -269,7 +269,7 @@ public function preSave(EntityStorageInterface $storage) {
     foreach ($this->bundle->entity->getFieldMap() as $metadata_attribute_name => $entity_field_name) {
       // Only save value in entity field if empty. Do not overwrite existing
       // data.
-      if ($this->hasField($entity_field_name) && ($this->get($entity_field_name)->isEmpty() || $this->sourceFieldChanged()) && ($value = $this->getSource()->getMetadata($this, $metadata_attribute_name))) {
+      if ($this->hasField($entity_field_name) && ($this->get($entity_field_name)->isEmpty() || $this->sourceFieldChanged()) && ($value = $this->getSource()->getMetadata($this, $metadata_attribute_name)) && $value !== NULL) {
         $this->set($entity_field_name, $value);
       }
     }
diff --git a/core/modules/media/src/MediaSourceBase.php b/core/modules/media/src/MediaSourceBase.php
index aa911c69b6..98c0e1ec13 100644
--- a/core/modules/media/src/MediaSourceBase.php
+++ b/core/modules/media/src/MediaSourceBase.php
@@ -125,7 +125,6 @@ public function defaultConfiguration() {
    */
   public function getMetadata(MediaInterface $media, $attribute_name) {
     switch ($attribute_name) {
-
       case 'default_name':
         return 'media:' . $media->bundle() . ':' . $media->uuid();
 
@@ -133,6 +132,8 @@ public function getMetadata(MediaInterface $media, $attribute_name) {
         $default_thumbnail_filename = $this->pluginDefinition['default_thumbnail_filename'];
         return $this->configFactory->get('media.settings')->get('icon_base_uri') . '/' . $default_thumbnail_filename;
     }
+
+    return NULL;
   }
 
   /**
diff --git a/core/modules/media/src/MediaSourceInterface.php b/core/modules/media/src/MediaSourceInterface.php
index 1036907507..0e0a5ba061 100644
--- a/core/modules/media/src/MediaSourceInterface.php
+++ b/core/modules/media/src/MediaSourceInterface.php
@@ -107,8 +107,8 @@ public function getMetadataAttributes();
    * @param string $attribute_name
    *   Name of the attribute to fetch.
    *
-   * @return mixed|false
-   *   Metadata attribute value or FALSE if unavailable.
+   * @return mixed|null
+   *   Metadata attribute value or NULL if unavailable.
    */
   public function getMetadata(MediaInterface $media, $attribute_name);
 
diff --git a/core/modules/media/tests/src/Kernel/MediaSourceTest.php b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
index 365370987f..252eab0ec4 100644
--- a/core/modules/media/tests/src/Kernel/MediaSourceTest.php
+++ b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
@@ -80,6 +80,16 @@ public function testMetadataMapping() {
     $media->save();
     $this->assertEmpty($media->get($field_name)->value, 'Field stayed empty.');
 
+    // Make sure that source plugin returns NULL for non-existing fields.
+    $this->testMediaType->setFieldMap(['not_here_at_all' => $field_name])->save();
+    $media = Media::create([
+      'bundle' => $this->testMediaType->id(),
+      'field_media_test' => 'some_value',
+    ]);
+    $this->assertNull($media->getSource()->getMetadata($media, 'not_here_at_all'), 'NULL is returned if asking for a value of non-existing metadata.');
+    $media->save();
+    $this->assertTrue($media->get($field_name)->isEmpty(), 'Non-existing metadata attribute was not mapped to the field.');
+
     // Define mapping and make sure that the value was stored in the field.
     \Drupal::state()->set('media_source_test_attributes', [
       $attribute_name => ['title' => 'Attribute to map', 'value' => 'Snowball'],